In a food processor, blend peppercorns, lemon zest, oil, salt and five tablespoons of sunflower seeds until texture is smooth. If mixture is too soft, blend in more sunflower seeds to form a paste.
Remove sunflower seed paste and set aside.
Season the sole fillets with salt and pepper.
Coat top side of fillets with sunflower seed paste, using the back of a tablespoon.
Press top side of the fish into the remaining sunflower seeds to form a nice crust.
Place the fish on a baking tray with parchment paper, and bake for 10-12 minutes, or until fish is firm and sunflower seeds have started to brown.
Remove from the oven and serve hot.
Serve with warm roasted chickpea salad (see recipe).