In a large re-sealable container, mix tamarind, garlic, honey and soy sauce to create a marinade. Add meat, coat thoroughly and marinate in refrigerator for 30 min. Meanwhile, in an 8-inch skillet over medium heat, dry roast mustard and cumin seeds just until aromatic, or until the seeds start to pop, about 1 to 3 min. Immediately transfer seeds to a small bowl so they will not continue to cook and burn. Next, heat vegetable oil in a wok over medium-high heat. When oil is hot, stir in peppers, onion and carrots. Cook for 4 to 5 min., stirring occasionally. Add steak and tamarind marinade, let steak brown on one side for 1 to 2 min., then stir in cumin, mustard and coriander. Brown other side for 1 to 2 min. for medium rare. Sprinkle in crushed red pepper if desired.
Serve over rice, noodles or a green salad.