Crab cakes: Mix the crabmeat, mayonnaise, egg, bread crumbs, scallions, the lime juice, 1/4 cup cilantro, and the hot sauce together in a small bowl. Season, to taste, with salt and pepper. Form the mixture into 8 (3/4-inch-thick) patties and refrigerate for 20 minutes.
Breading: Mix the bread crumbs and 1/4 cup of cilantro on a plate. Carefully turn the patties in the bread crumb mixture until coated on both sides.
In a large nonstick skillet, heat the olive oil over medium-high heat. In batches, fry the crab cakes until golden, about 3 minutes each side.
Guacamole: Coarsely mash the avocados in a medium bowl. Lightly mix in the onion, cilantro, and lime juice. Season with salt and pepper, to taste.
Transfer the crab cakes to a serving platter, top each cake with a tablespoon of guacamole, and serve.
Spicy Crab Cakes Topped with Guacamole