Turn the oven on the broil setting.
Sprinkle both sides of the steak with salt and pepper.
Place steak on a foiled lined rimmed cookie sheet. Place in the oven and broil each side for 4 to 7 minutes, depending on how you like your steak. Remove from oven and immediately turn oven down to 425 degrees F. Place steak on cutting board. Let stand for 10 minutes to allow juices to redistribute. Slice into very thin pieces, or small chunks. Toss with half of the barbecue sauce, setting aside the other half of the sauce for later.
Remove foil from cookie sheet and discard.
Place the waffle fries in a single layer on the cookie sheet. Place in oven for 10 minutes. Remove from oven and flip the fries. Place back in oven for 7 minutes. Remove pan from oven and immediately turn down the oven to 400 degrees F.
While the oven temperature is adjusting, toss the steak on top of the waffle fries as evenly as possible. Toss the cheese over top as evenly as possible.
Place the pan back in the oven and cook for about 5 to 8 minutes, depending on how you like your cheese. Remove from oven and turn oven off.
Drizzle the remaining barbecue sauce over top of the nachos, then use a large spoon to drizzle the salsa randomly over top. Toss chopped onions over top. Toss the cilantro over top. Sprinkle with coarse salt, if desired.
Serve immediately with a big old nacho loving smile!