For my little toaster oven I set at 300F. If you are using the broiler on a standard stove, I'd move it 1level away from the burner.
My marinade is cranberry juice or lemon juice/ kombucha tea, wine, or water/ spice herbs
paprika, turmeric, onion powder, garlic, marjoram, parsley or cilantro, oregano, ginger, dry mustard, whatever is on hand.
The fruit juice, and wine or tea are what tenderize the meat.