My personal 1st choice preference and one I always have on hand for guests that want to try something other than the typical red sauces is a simple vinegar pepper sauce. Its not on the meat while cooking but is used as a "dressing" after the meat has been cooked and pulled. I especially like it for BBQ pork sandwiches.
1 part white vinegar
1 part cider vinegar
table salt
black pepper
red pepper flakes
Pot it in a pot. Simmer it on the stove for a few minutes or so. Let it cool. Put it in a container and let it sit overnight.
Those are the base elements. The salt and pepper should be to taste. If you've never had a similar sauce before that might seem ambiguous. Try to take into account your guests. If they like tangy, spicy, extra hot, salty, etc. If you ever make a salad dressing, the process is roughly the same.
The end result should be tangy and spicy. Maybe you make a small amount a few days before and see what you think.
A bit of an atypical suggestion, but I promise it's awesome: two parts maple syrup to one part soy sauce. It tastes AMAZING, and also works really well with salmon. Can supplement with garlic, pepper, and chives/green onions according to your tastes.
Whilst tomatillos are ideal, unripe tomatoes do work a treat especially because I cook the pork with the sauce, plenty of green chilis and a good dose of lime juice for extra acidity. For other applications I’m sure there’s a more noticeable difference.
