Cut tempeh into strips, one inch wide by two inches long. Put in bowl and cover with barbecue sauce. Marinade for about 30 minutes at room temperature. Preheat oven 350°F.
Meanwhile, sauté the garlic, onion and peppers in olive oil until soft and golden. Set aside. Drain excess barbecue sauce from tempeh, reserving for use later, if desired.
Gently toss tempeh and sautéed garlic, onions and peppers. Put mixture in casserole or baking pan and bake uncovered at 350° F for 25 minutes, stirring occasionally, adding reserved
barbecue sauce if it needs moistening.