Start with the minty pea mayo. Mix peas, mint, mayo and a drizzle of lemon juice in a high speed blender. Season to taste with salt and pepper and set aside.
Wash and half the radishes. Wash and pad dry the spinach.
Heat up some vegetable oil in a saucepan or grill pan. Season your fish fillets with salt, pepper and a drizzle of lemon. Grill the fish for about 3 minutes on each side on medium heat. Take it out of the pan and let it rest in some tinfoil. Now sautè your radishes for 2 minutes in the pan and also char-grill the lemon halfs in your pan.
Now assembly your fish burgers. Put some minty pea mayo on the bottom bread roll, add some spinach and top with fish. Now add your sautè radishes and serve with charred lemon. Bon Appetit!