Chef John's Green Sauce
This is about as primitive as it gets. Take some garlic, capers, anchovy, and parsley, and smash it up in a molcajete. Add a little oil and vinegar, possibly a pinch of salt and pepper, and you have maybe the world's greatest grilled meat condiment. I guessed at these amounts as this is not a recipe that requires precise measurements; do everything to taste.
Recipe Summary test
You can use any vinegar or lemon juice in place of white wine vinegar.