1) For the burgers: in a food processor, combine the shrimp, egg, coriander, garlic, 170 g bread crumbs, poblano chilli, salt, and pepper. Process until the mixture is a coarse puree. Form the mixture into six patties and set aside (if the mixture is too wet, add additional bread crumbs, one tablespoon at a time, until the mixture can be molded easily).
2) Put a griddle pan over medium-high heat or preheat a gas or charcoal grill. Brush the patties with vegetable oil and griddle until golden, about three minutes per side, depending on the thickness.
3) For the avocado aioli: scoop the avocado pulp into the bowl of a food processor. Add the mayonnaise, lime juice, garlic cloves, serrano chilli and coriander. Process until smooth. Season with salt and pepper, to taste.
4) To assemble: serve the shrimp burgers on buns, topped with a dollop of avocado aioli, sliced tomato, and lettuce.