Prep the steak: Freeze the beef for 20–30 minutes to firm it up, then slice very thin against the grain. Pat dry with paper towels.
Season simply: In a bowl, toss the beef with salt, pepper, garlic powder, onion powder, and smoked paprika.
Add Worcestershire or soy. Set aside.
Slice the veg: Cut peppers and onion into thin strips. Slice mushrooms if using.
Rinse spinach.
Cook the vegetables: Heat a large skillet over medium-high. Add 1 tablespoon oil. Sauté onions 2–3 minutes until starting to soften.
Add peppers and mushrooms. Cook 5–7 minutes until browned with a little bite. Season with a pinch of salt and pepper.
Transfer to a bowl.
Sear the steak in batches: Return the skillet to high heat. Add a light drizzle of oil. Spread a single layer of beef and sear 60–90 seconds per side.
Do not overcrowd. Remove to a plate and repeat with remaining beef.
Wilt the greens (optional): Toss spinach into the hot skillet for 30–60 seconds until just wilted.
Make the high-protein cheese sauce (optional): Blend Greek yogurt, cottage cheese, Parmesan, and Dijon until silky. Warm gently in a small pan over low heat for 1–2 minutes, stirring.
Do not boil.
Build the bowls: Add your base (cauliflower rice, quinoa, or brown rice). Pile on peppers and onions, then steak. Lay slices of provolone over the hot mixture and cover the bowl or tent with foil for 1–2 minutes to melt.
Or spoon on the protein cheese sauce.
Finish and serve: Add hot sauce, jalapeños, or parsley if you like. Taste and adjust salt and pepper. Eat right away while the cheese is gooey.