Balık Ekmek (Grilled Mackerel Sandwich)

• 1 ¼ lb mackerel fillets, about 4 fillets, skin on, pin bones removed
• 4 crusty bread rolls, or split a baguette into 4 pieces
• 2 tbsp olive oil Swap
• 2 tbsp fresh lemon juice, plus wedges for serving Swap
• 1 small red onion, thinly sliced Swap
• 1 cup romaine lettuce, shredded
• 1 medium ripe tomato, sliced
• 1 tsp kosher salt
• ½ tsp black pepper Swap
• 1 tsp sumac Swap

Equipment

grill or cast-iron skillet, fish spatula