A marinade of some kind; depends on the protein.
Fish (usually tilapia), shrimp: Lime juice, black pepper, sea salt, cayenne pepper, chili pepper, crush garlic, diced red onion or fresh chives. Grill (or broil if no grill.)
Steak (usually skirt steak): cross hatch score the meat, then marinate in 2 to 1 ratio of olive oil and red wine vinegar (softens the muscle fibers), add black pepper, sea salt cayenne pepper, chili pepper, crush garlic, diced red onion. After grilling/broiling a few min on each side, I let it rest and slice into strips across the grain.