Place beef fat trimmings in food processor and blend until smooth. Transfer to skillet over medium heat and cook until fat has rendered out. Drain liquid fat and set aside. Discard solid fat.

Place rendered fat into large skillet on medium-high heat and add onion, garlic, and red bell pepper. Season with salt and pepper and stir frequently until tender (about 5 minutes.)

Add roast beef slices and beef stock, lower heat, and simmer for 15 minutes, stirring frequently and separating beef slices.

Arrange TOSTITOS^® on platter and top with juicy beef mixture. Top with hot pickled peppers and serve. Optionally, top with grated provolone and place in oven for 3-4 minutes.