Preheat oven to 400F
Toss about 100g of the garlic with the olive oil, 1/2 tsp salt, and all the thyme
Loosely wrap in aluminum foil and roast in the oven for about 30 minutes, until soft and browned all over
Once done, put all the garlic, the onion, remaining salt and pepper in the work bowl of blender or food processor
In a 1 cup measuring cup, add 3 Tbsp apple cider vinegar, then fill to 1/2 cup line with distilled white vinegar
Add to garlic/onion mixture and blend until smooth
Add oil and blend until emulsified
Add additional salt/pepper to taste
Makes about 12 oz, store in the refrigerator