Did some experimenting with a pound of steak tips.
Marinated them for about 2 hours in red wine vinegar, EVOO, salt, pepper, garlic powder, a bit of ketchup, worcestershire, and soy sauce.
Sliced a small onion, a handful of sliced sweet peppers and this is where I screwed up -- a handful of sliced button mushrooms.
Some EVOO in a pan, softened the onions, added the sweet peppers also to soften. Removed from the pan, put in the mushrooms to saute. Removed those, cranked up the heat, and added the steak tips to sear to about a medium rare. Added the marinade and softened veggies to heat through.
Served on spaghetti.