For the Tomato-Fennel Relish:

Ingredients

• 2/3 cup seeded and finely chopped firm ripe plum or vine-ripened tomatoes
• 1/3 cup finely chopped fennel
• 3 tablespoons finely chopped sweet onion
• 1/2 teaspoon grated fresh lemon zest
• 1 tablespoon fresh lemon juice
• 3/4 teaspoon fresh thyme leaves
• 1 tablespoon garlic-flavored olive oil
• 1/8 teaspoon kosher salt
• 1/8 teaspoon freshly ground black pepper

For the Saffron Mayonnaise:

• 1/4 teaspoon saffron threads
• 1 tablespoon fresh lemon juice
• 3/4 cup good-quality mayonnaise
• Pinch kosher salt
• Pinch freshly ground black pepper

For the Patties:

• 1 3/4 pounds skinless, boneless red snapper fillets (or any other firm-textured white lean fish), coarsely ground (in small batches) in a food processor or chopped into about 1/4-inch pieces by hand
• 3/4 pound peeled and deveined large raw shrimp, cut into about 1/4-inch pieces
• 5 egg whites
• 1 1/4 teaspoons chopped fresh thyme leaves
• 1 teaspoon kosher salt
• 1/2 teaspoon freshly ground black pepper
• 1 1/4 to 1 1/3 cups panko (Japanese bread crumbs), or as needed
• Canola oil, for brushing on the grill rack (recommended: Colavita All Natural)
• 12 slices, about 1/2 to 3/4-inch-thick, French bread, cut from center of 1 loaf or 2 loaves
• Garlic-flavored olive oil, for brushing on both sides of bread slices

Directions