Instructions:
1. Preheat your grill or stovetop pan over medium-high heat.
2. Divide the ground beef into four equal portions and shape them into burger patties. Season both sides of the patties with salt and pepper.
3. In a separate pan, heat the vegetable oil over medium heat. Add the sliced onions and bell peppers to the pan and cook until they are soft and lightly caramelized, about 8-10 minutes. Remove from heat and set aside.
4. Place the burger patties on the grill or stovetop pan, and cook for about 4-5 minutes per side, or until they reach your desired level of doneness.
5. During the last minute of cooking, place a slice of provolone cheese on top of each patty to let it melt.
6. While the patties are cooking, lightly toast the hamburger buns on the grill or in a separate toaster.
7. Assemble the burgers by placing a patty with melted cheese on the bottom half of each bun. Top the patty with a generous portion of the sautéed onions and bell peppers. You can also add additional toppings like mayo, ketchup, or mustard if desired.