How to Freeze Herbs in Olive Oil: A Step-by-Step Guide to Herb-Infused Ice Cubes

Why Freeze Herbs in Olive Oil Instead of Water or Dry

Freezing herbs in olive oil serves a different purpose than freezing them in water. The oil acts as a protective medium that coats each herb piece, reducing the amount of air contact and slowing the oxidation that turns herbs brown and dull. Herbs frozen this way retain more of their essential oils and a brighter color than those frozen in water cubes.

The oil also makes the cubes ready to use directly in cooking. A frozen herb-oil cube can be dropped straight into a hot pan, where the oil melts and the herbs release their flavor into the dish. This works well for sautés, roasted vegetables, pasta sauces, soups, and braises. It eliminates the step of thawing and draining watery herb cubes, which can dilute a sauce.

Choose a mild olive oil for this method. Extra-virgin olive oil has a strong, fruity flavor that can overpower delicate herbs like parsley or chives. A lighter olive oil or a blend of olive oil and a neutral oil like grapeseed works better when you want the herb to be the dominant flavor. The oil also freezes at a lower temperature than water, so the cubes stay slightly soft and are easier to pop out of the tray.

Stage 1: Selecting and Preparing Herbs for Freezing

Start with herbs that are dry. Moisture on the leaves turns to ice crystals inside the cube, which can make the texture watery and cause the herbs to clump. Wash the herbs thoroughly under cold running water to remove dirt and any small insects, then dry them completely. The most effective way is to spin them in a salad spinner, then lay them on a clean kitchen towel and pat the tops dry. Let them sit for 10 to 15 minutes to ensure no water remains.

Not all herbs freeze equally well in oil. Hardy herbs with sturdy leaves, such as rosemary, thyme, sage, oregano, and winter savory, hold their structure and flavor well. Softer herbs like basil, mint, cilantro, parsley, and dill also work, but they will darken and soften more. Basil is a special case: it benefits from being blanched briefly before freezing, which deactivates the enzymes that cause it to turn black. Drop basil leaves in boiling water for 10 seconds, then plunge them into ice water and pat dry before chopping.

Remove any thick stems, especially from woody herbs like rosemary and thyme. The stems are edible but tough, and they take up space in a cube that could hold more leaf material. For soft-stemmed herbs like cilantro and parsley, you can chop the stems finely along with the leaves, since they contain flavor and freeze well. The goal is to have uniformly sized pieces, about 1/4 inch or smaller, so they pack evenly into the tray compartments.

• Hardy herbs: rosemary, thyme, sage, oregano, winter savory
• Soft herbs: basil, mint, cilantro, parsley, dill
• Blanch basil for 10 seconds in boiling water, then ice bath, before chopping
• Chop all herbs to about 1/4 inch pieces for even packing

Stage 2: Chopping and Filling the Ice Cube Trays

Once the herbs are dry and prepared, chop them with a sharp chef's knife. A dull knife crushes the leaves and releases their moisture, which is not what you want. Chop in batches rather than all at once, keeping the pieces uniform. If you are working with a large quantity, a food processor with a pulse setting can work, but be careful not to over-process, which turns the herbs into a paste.

Fill each ice cube compartment about halfway to two-thirds full with chopped herbs. Do not pack them down tightly. The herbs need a little room for the oil to surround them completely. If the compartment is overfilled, the herbs will stick out above the oil level, and those exposed pieces will dry out and turn brown in the freezer. Leave a small gap at the top of each compartment so the oil can expand slightly as it freezes.

For a more concentrated herb cube, you can fill the compartments nearly full with herbs and use just enough oil to fill the gaps. For a milder cube, use more oil and fewer herbs. Think about how you will use the cubes. A cube with mostly herbs and a little oil works well for adding to a sauce or soup at the end of cooking. A cube with more oil is better for starting a sauté or roasting vegetables.

Stage 3: Adding the Olive Oil and Freezing

Pour the olive oil slowly over the chopped herbs in each compartment. Use a measuring cup with a spout or a small spoon to control the flow. Fill each compartment until the oil just covers the herbs, leaving about 1/8 inch of space at the top. The oil will expand slightly as it freezes, so this small gap prevents overflow and makes the cubes easier to remove from the tray.

If you are using a silicone ice cube tray, you can place it directly on a flat baking sheet before filling. This keeps the tray stable and prevents spills when you move it to the freezer. For rigid plastic trays, filling them in place on a shelf is easier, but be careful not to overfill, since moving a full tray can cause the oil to slosh.

Place the filled tray in the freezer on a level surface. Freeze for at least 4 to 6 hours, or preferably overnight. The cubes are ready when they are solid and no longer soft to the touch. Because olive oil freezes at a lower temperature than water, the cubes may feel slightly soft even when fully frozen. To test, press the bottom of a silicone tray compartment; if the cube holds its shape, it is ready.

The freezing time depends on your freezer temperature and the size of the compartments. Standard ice cube compartments take about 4 hours. Larger, jumbo-sized compartments can take 8 hours or more. Do not stack trays on top of each other while freezing, because the air circulation is reduced and the freezing takes longer.

Stage 4: Removing the Cubes and Storing Them Long-Term

Once the cubes are fully frozen, remove them from the tray. For a silicone tray, push up on the bottom of each compartment to release the cube. For a rigid plastic tray, run the bottom of the tray under warm water for a few seconds to loosen the cubes, then press them out. Do not use hot water or a knife to pry them out, as this can damage the tray or break the cubes.

Transfer the cubes to a freezer-safe container or a zip-top freezer bag. If using a bag, press out as much air as possible before sealing. Air in the bag causes freezer burn and can give the oil an off flavor over time. Label the container with the type of herb and the date. Frozen herb-oil cubes keep their best quality for 6 to 9 months, though they remain safe to eat indefinitely as long as the freezer temperature stays at 0°F (-18°C) or below.

If you are freezing multiple types of herbs, store them in separate containers or use small bags within a larger container. This prevents the flavors from mingling. You can also freeze a mixed herb cube, such as a blend of rosemary, thyme, and oregano, which works well for Mediterranean dishes. Write the blend name on the label so you know what you are grabbing.

• Push from the bottom of silicone trays; run warm water on the back of rigid trays
• Store in freezer bags or airtight containers, pressing out excess air
• Label with herb name and date; use within 6 to 9 months for best flavor
• Keep different herbs in separate containers to avoid flavor mixing

Stage 5: Using Herb-Oil Cubes in Cooking

Herb-oil cubes are designed for cooking, not for garnishing fresh dishes. Drop a frozen cube directly into a hot pan, a simmering pot of soup, or a roasting pan. The oil melts and the herbs release their flavor as the dish cooks. For a pan sauté, add the cube at the same time you would add oil and aromatics, and let it melt before adding other ingredients.

For sauces and soups, add the cube near the end of cooking so the herbs retain more of their fresh flavor. If you add it too early, the prolonged simmering will dull the herb's taste. For roasted vegetables, toss the frozen cubes with the vegetables before roasting; the melting oil coats the vegetables evenly.

One cube is roughly equivalent to 1 to 2 tablespoons of chopped fresh herbs combined with about 1 tablespoon of oil. Adjust the number of cubes based on your recipe. If a recipe calls for 2 tablespoons of fresh chopped rosemary, you would use about one standard herb-heavy cube. Taste as you go, since frozen herbs can be slightly more concentrated than fresh ones after the cell walls break down during freezing.

Do not use these cubes for salads, dressings, or other uncooked applications where the texture of thawed herbs would be unappealing. The freezing process softens the herbs, so they are best used in cooked dishes where their texture blends in.

Common Mistakes and How to Avoid Them

The most common mistake is using wet herbs. Moisture trapped in the oil creates ice crystals that make the cubes watery and cause the herbs to clump together. Always dry herbs thoroughly before chopping. A salad spinner followed by a towel pat-down is the most reliable method.

Another frequent error is overfilling the compartments. When the oil expands during freezing, it can push herbs above the surface, exposing them to air. This causes browning and freezer burn. Fill compartments only two-thirds full with herbs and leave a small gap at the top for expansion.

Using a low-quality oil with a strong or rancid taste can ruin the cubes. Taste your olive oil before using it. If it has a bitter or stale flavor, the frozen cubes will carry that flavor into your food. Also, avoid using flavored oils, such as garlic- or chili-infused olive oil, unless you want that extra flavor in every dish.

Finally, do not forget to label. After a few weeks in the freezer, all herb cubes look the same. A permanent marker and masking tape on the container will save you from guessing. Write the herb name and the date you froze them, and you will always know what you are cooking with.