Light a grill. In a medium bowl, mash the avocados, sour cream, jalapeńo, red onion, cilantro and 3 tablespoons of the lime juice. Season the guacamole with salt and pepper and press a piece of plastic wrap directly onto the surface of the guacamole.
In a large bowl, toss the cabbage with the 2 tablespoons of vegetable oil and the remaining 2 tablespoons of lime juice. Season with salt and pepper.
Brush the fish with oil and season with salt and pepper. Grill over moderately high heat until lightly charred and cooked through, about 10 minutes. Transfer the fish to a platter and pull off the skin.
To assemble each taco, spread a dollop of guacamole on a tortilla. Top with a piece of fish, a few tomato slices and a large spoonful of the cabbage slaw. Serve with the hot sauce and lime wedges.