Add the tofu, garlic, apple cider vinegar, cayenne pepper, and salt to a food processor. Blend until mostly smooth, then pour in ¼ cup of oil in a slow stream until the sauce is airy and whipped.
Transfer any leftovers to an airtight container, and store in the fridge for up to 1 week. Always use a clean utensil when handling.
Notes
Makes about 1 1/2 cups. Serving size: about 2 tablespoons.