Form the beef into four 6-ounce patties, about 3/4 inch thick; press the center of each patty with your thumb to make a 1/2-inch-deep indentation. Season the patties on both sides with salt and pepper. Lightly brush the grill grates with the vegetable oil, then grill the patties, indentation-side up, until marked on the bottom, about 5 minutes. Flip and cook until marked and slightly firm, about 3 more minutes for medium doneness. Remove the patties to a plate and let rest 5 minutes. Grill the rolls, cut-side down, until lightly toasted, about 1 minute. Toss the avocado and lime juice in a bowl and season with salt and pepper. Spread the refried beans on the bun bottoms, then top with the burger patties, cheese, avocado, pickled jalapenos and lettuce. Cover with the bun tops.