For the steak: Prepare a grill for medium-high heat.
Season the steak generously on all sides with salt, pepper and either olive oil or canola oil. Add the steak to the grill and cook until it releases from the grill, about 5 minutes. Flip and cook until desired doneness, another 3 to 4 minutes for 120 to 125 degrees F. Remove to a plate, sprinkle evenly with the Parmesan and cover loosely with aluminum foil. Rest for 10 minutes before slicing.
For the topping: In a large pan on medium heat, add 2 tablespoons olive oil and the bacon. Cook, stirring, until the bacon is crisp, about 5 minutes. Remove with a slotted spoon to a paper towel-lined plate. Add the mushrooms to the pan and cook until wilted and tender, 3 to 5 minutes. Season the mushrooms with salt and pepper, remove with a slotted spoon to a large bowl and add the reserved bacon to the bowl. If more oil is needed in the pan, add a tablespoon, then add the onions. Cook, without stirring, until the onions begin to char. Stir the onions and continue to cook until tender, 5 to 8 minutes. Remove to the bowl. Add a little oil to the pan, then add the bell peppers and Italian seasoning and stir to combine. Cook until slightly tender, 3 to 5 minutes, then remove to the bowl. Add the tomatoes and red chile flakes to the pan and cook until the tomatoes begin to burst, 5 to 8 minutes. Transfer to the bowl as well. Toss the mixture together with the basil and serve on top of the sliced steak.