Preheat oven to 325 degrees F (165 degrees C). Coat the inside of a roasting pan with about 1 tablespoon oil.
Mix flour, grill seasoning, seasoned salt, garlic powder, and black pepper to together in a shallow bowl. Dredge steak in the flour mixture until all sides are coated, shaking off excess. Place coated steak on a plate and let rest for 5 minutes.
Heat enough oil in a skillet to coat the bottom of the pan over medium-high heat. Add steak, a few pieces at a time, to the hot oil; fry until browned, 2 to 3 minutes per side. Transfer browned steak to the prepared roasting pan.
Mix beef broth, cream of mushroom soup, and diced tomatoes with green chile peppers together in a bowl; pour into the roasting pan. Top broth mixture with onion slices.
Bake in the preheated oven until steak is tender, about 90 minutes. An instant-read thermometer inserted into the center should read 145 degrees F (63 degrees C).
The nutrition data for this recipe includes the full amount of the flour mixture. The actual amount consumed will vary. We have determined the nutritional value of oil for frying based on a retention value of 10% after cooking. The exact amount will vary depending on cooking time and temperature, ingredient density, and the specific type of oil used.
Per Serving: 334 calories;12.7 g fat;
35 g carbohydrates;
19.5 g protein;
27 mg cholesterol;
2657 mg sodium.