1/2 cup aquafaba or unsweetened soy milk
1 tablespoon lemon juice or vinegar
1 teaspoon mustard
1/2 teaspoon salt
1 to 1 1/2 cups neutral oil
Add aquafaba or soy milk, lemon juice or vinegar, mustard, and salt to a blender or mixing bowl
Blend or whisk until combined
Slowly add oil in a thin stream while blending or whisking continuously
Continue until thick and creamy
Adjust salt, lemon juice, or mustard to taste
Store in a covered container in the refrigerator