01 - In a bowl, gently combine ground beef with salt and black pepper. Shape into 4 even patties.
02 - Preheat grill or skillet to medium-high heat. Cook patties for 3 to 4 minutes on each side until desired doneness. If using cheese, place a slice on each patty during the last minute and cover to melt.
03 - While patties cook, toast burger buns until golden brown.
04 - In a small bowl, mix mayonnaise, Dijon mustard, and lime juice. Spread evenly onto cut sides of each bun.
05 - Layer lettuce, tomato, and red onion on bottom bun. Add cooked beef patty, top with avocado slices, then place the top bun. Add optional pickles, jalapeños, or sprouts as desired.
06 - Serve immediately for optimal freshness and flavor.