1/3 cup finely chopped yellow onion
2 tablespoons fresh lime juice
1/2 teaspoon paprika
1/4 teaspoon freshly ground pepper
4 slices bacon, cut in half crosswise
2 tablespoons olive oil
1 tablespoon chili powder
1 tablespoon finely chopped garlic
4 mahi-mahi fillets (or other meaty fish, such as swordfish), skin on, each about 8 ounces, 1 inch thick
vegetable oil for brushing cooking grate
8 slices bread, each 1/2 -inch thick
4 romaine lettuce leaves
8 slices tomato
Prepare a charcoal fire, medium hot.
In a small bowl, whisk together mayonnaise, onion, lime juice, paprika and pepper. Cover and refrigerate until needed.
Cook bacon until browned, 8 to 10 minutes. Transfer to paper towels and drain.
In a small bowl, whisk together olive oil, chili powder and garlic. Brush this mixture on the flesh side on the fillets. Lightly brush the cooking grate with vegetable oil. Place the fillets, flesh side down, directly over medium heat and grill, turning once, until flesh is opaque, 10 to 13 minutes. Remove skin before serving.
When the fish is almost cooked, grill the bread directly over medium heat, until lightly toasted, about 2 minutes a side. Evenly spread one side of the bread with the refrigerated mayonnaise mixture.
To build each sandwich, start with a slice of toasted bread, a lettuce leaf, two tomato slices, 2 half slices of bacon, the fillet, then the other slice of toasted bread.
bacon recipe source: Rob Kasper, "Gone fishing for a good grilled sandwich," The Baltimore Sun, September 12, 1999; Weber's Art of the Grill: Recipes for Outdoor Living, by Jamie Purviance (Chronicle Books, 1999)