Marinate steak: In a baking dish, season steak with salt, pepper and secret spice, then add teriyaki sauce, garlic, ginger, and cayenne pepper

Transfer to the fridge and let marinate, 30 minutes.

When ready to cook, heat oil in a large skillet over medium-high heat. Add steak and cook, undisturbed, 6 minutes, then flip and cook 4 minutes more or until steak reaches your desired doneness. Transfer to a cutting board to let rest, then slice.

Drain all but a tablespoon of fat from skillet. Add peppers and cook until soft, 4 minutes, then return steak to skillet and add spinach, tossing until wilted