Preheat oven to 425°F. Combine mushroom powder, tomato powder, everything bagel spice, vinegar, tamari, sugar, hot sauce, and ¼ tsp pepper in small bowl and set aside. Combine potato, 2 tsp vegetable oil, a pinch of salt, and ¼ tsp pepper on baking sheet and toss. Roast until potato is lightly browned and crisp in places, 20 to 25 minutes.

Meanwhile, toast buns directly on oven rack until lightly browned, 2 to 4 minutes. Set aside.

Heat 1 tbsp vegetable oil on one side of large nonstick skillet over medium-high heat. Add burgers and cook until browned and heated through, 4 to 6 minutes per side. On other side of skillet, place cheese in skillet in 2 mounds and sprinkle each with half the crispy onions. Spread each into 2-inch circle and cook until cheese forms crispy disks, 3 to 5 minutes.

Place bottom half of each bun on plates. Top each with burger and disk of crispy cheddar onions. Drizzle with as much steak sauce as you'd like. Close steakhouse burgers with top buns. Serve with potato wedges and remaining steak sauce for dipping. Dig in!

For 4-serving meal, double all ingredients. You may need to cook in batches, in larger cooking vessels, or for longer cook times. Follow visual cues in 2-serving recipe.