Before heating oven, arrange one oven rack near broiler and one close to the bottom of the oven. Heat oven to 450°. Line a large sheet pan with foil and coat lightly with oil or non-stick spray
Toss potatoes with 1 Tbsp olive oil and 1 Tbsp seasoning. Arrange on baking sheet in a single layer, cut side down. Roast on bottom rack until just tender, approximately 20-25 minutes.
While potatoes cook, toss pepper slices with 1 Tbsp seasoning and rub steak all over with 1 Tbsp oil and remaining seasoning.
Carefully remove pan from oven and use a spatula to move potatoes to edge of pan. Place steak and peppers in the center in an even layer.
Set oven to broil. Broil until steak is browned 4-5 minutes per side for medium-rare or to desired doneness. Remove from oven and allow steak to rest on pan for 5 minutes. Slice and serve immediately.