Place fillets in the dish and turn to coat. Let sit at room temperature for 10–15 minutes (no more than 30 minutes) to pick up flavor without cooking the fish.

Grill

Preheat a grill or grill pan to medium-high (about 400°F / 200°C). Oil grates lightly. Grill fillets 3–4 minutes per side, until opaque and an instant-read thermometer reads 135–140°F (57–60°C). Do not overcook; fish should flake easily. Transfer to a plate and rest 3 minutes.

Chipotle Aioli

In a small bowl combine mayonnaise, minced chipotle, adobo sauce, lime zest, lime juice, honey and salt. Whisk until smooth and homogeneous. Taste and adjust: add more adobo for heat, more honey for sweetness, or a pinch more salt. Refrigerate until ready to use.

Yuzu Pickles

Place sliced cucumber and red onion in a bowl or jar. In a separate bowl whisk rice vinegar, yuzu juice, sugar and salt until sugar dissolves. Pour the pickling liquid over vegetables, press down to submerge, and let sit at least 15 minutes at room temperature or up to 2 hours in the refrigerator. Reserve 2 teaspoons of the brine for sandwich finishing.

Sandwich Build

Toast rolls

Butter the insides of the rolls and toast on the grill or in a skillet over medium heat until golden, about 1–2 minutes per side.

Assemble

Spread 1 to 1 1/2 tablespoons of chipotle aioli on the bottom half of each toasted roll. Place a leaf of lettuce, a slice of tomato (season lightly with salt and pepper), then a grilled grouper portion. Top the fish with a generous spoonful of yuzu pickles (cucumbers and onions) and drizzle about 1/2 teaspoon of the reserved pickle brine over the fish to add bright acidity. Finish with additional aioli on the top bun if desired, then close the sandwich.

Serve

Serve immediately while the fish is warm. Optionally serve with extra lime wedges and remaining chipotle aioli on the side.