I'm in the process of moving, so I haven't had time for fancy recipes. Luckily there are a few things that can make anything tasty: salt and acid. Adding a dash of acid to a dish can really improve the flavor profile. For example, on Sunday I made pork chops for Chris with rosemary, sea salt, pepper, and a dash of peach vinegar that I got from this awesome store called The Filling Station. Some great ideas for adding acid include: vinegars, fermented vegetables, and acidic pastes.
My favorite vinegars are coconut vinegar, balsamic vinegar, and flavored vinegars. You can make your own flavored vinegar, like this fig vinegar or this peach vinegar. Trader Joes has some excellent vinegars like tangerine vinegar. The aforementioned Filling Station has at least 10 varieties and many online retailers also sell flavored vinegars.
Fermented vegetables also add a tangy acid kick. Many restaurants I like serve pickled vegetables alongside entrees. Lot 2 in Windsor Terrace used to serve chicken confit with silky pickled mushrooms, which was amazing.
Many acidic pastes are obvious: like tomato paste. There is a reason why tomatoes have been enthusiastically adopted by so many cultures. Another great one, which is the secret in many authentic Thai recipes, is tamarind paste. Many BBQ sauces actually contain this and it definitely tastes great with meat. I often marinate liver or heart with tamarind paste, lime juice, chili, ginger, and garlic overnight, which balances out some of the "mineral" flavor of these offal cuts.
What acidic ingredients do you cook with?
Edit: And duh...citrus! Using exotic citrus is also lots of fun!