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Fill approximately 2/3 of the way to the top with your herbs. Fill almost to the top but take care not to overfill or spill. Stack the trays if you are creating multiples. Don't leave trays in the freezer for too long as other food in the freezer may intermingle with the cubes, compromising the taste. Release the cubes in a clean plate or surface. Make sure each bag is clearly marked with the date and contents of each cube. Use cubes for up to 6 months or for two seasons (freeze in the summer and use for fall and winter meals).
Fill each compartment of the ice cube tray with herbs. Add olive oil to each compartment of the ice cube tray. Cover the tray with plastic wrap and place in freezer. Freeze overnight or for several days. Remove trays from freezer and pop cubes from tray. Place the cubes in plastic freezer bag. Return the well-sealed bags to the freezer and use as needed.