Put the frozen herbs with the oil in a bowl and let them thaw a little. Meanwhile, chop the garlic cloves and mash them on top of the salt with a knife.
Add the garlic and salt mixture to the herbs and oil and mix with the room temperature margarine until everything is well mixed and the butter is creamy. Add a little pepper to taste.
Also suitable for freezing and tastes good even to non-vegans. I always do double the amount. I then freeze that in four parts of 160 grams each, i.e. about 4 servings.