This spicy sauce, seasoned with plenty of lemon juice, goes well with fish dishes. For grilled meats, add a bit of red-wine vinegar in addition to the lemon juice.
Combine onion, garlic, oil, Scotch Bonnet (or jalapeno), parsley, chives (or scallion tops), thyme, salt and pepper in a small bowl. Stir in boiling water and let stand until cool. Stir in lemon juice.
Make Ahead Tip: Cover and refrigerate for up to 2 weeks.