Finely chop the shrimp until chunky, not paste like.
Mix shrimp with breadcrumbs, egg, garlic, spices, salt, and pepper until just combined.
Shape into 4 patties about ¾ inch thick.
Cook patties in olive oil over medium heat for 3 to 4 minutes per side until golden and cooked through.
Mash avocados and mix with onion, tomato, garlic, lime juice, salt, and pepper.
Assemble burgers with lettuce, shrimp patty, guacamole, tomato, and buns, then serve immediately.