Cut strip steak crosswise into 1-inch-wide strips. 

In a small bowl, mix cumin, chili powder, garlic powder, sea salt and two-thirds of the oil.

Put sliced beef, bell peppers and onions into a large zip-top bag. Pour in marinade, knead to coat, and transfer to refrigerator for 15 minutes to marinate. 

Pour the remaining oil into a large safe nonstick or cast iron pan over medium-high heat. 

When shimmering, add the beef and vegetables, turn heat to high, and cook until veggies are crisp-tender and beef is cooked to desired temperature, about 6 minutes.  Remove from heat and stir in the lime juice. 

Serve with warm tortillas and guacamole