Set aside a tbsp of the flour for dusting the fish. Make the seaweed batter by whisking together the flour, beer, Savoury Umami and baking powder until smooth. Leave to sit for at least 30 mins.
While the batter is resting, prepare the potatoes by cutting into skinny chips. Leave the skin on for a rustic finish. Next, cook the peas and drain. Set these aside in a bowl.
To cook the fish: dust the cod with a little flour then dip into the batter, ensuring that the fish is well coated. Place carefully in a preheated fryer, at 180°C. Cook until the fish is a golden brown colour and the batter is crisp.
While the fish is cooking, warm the butter in a pan then pour on to the cooked peas, adding the mint leaves and a squeeze of lemon. Crush the peas until mushy but chunky (this can be done by hand or in a food processor), and season with Salt & Peppery.
Remove the fish from the fryer and drain on kitchen paper to remove excess oil. Keeping the fish warm, fry the chips for 5-6 minutes, or until golden.
While the chips are cooking, take half of the lemon and put flesh side down in a hot frying pan or on a hot skillet, to char it. This will caramelise the lemon to remove the bitterness. Remove from the pan when the flesh is charred.
When the chips are golden, remove from the oil and drain on kitchen paper. Season with a generous sprinkle of Cornish Sea Salt Flakes.
Serve the crispy fish, chips and mushy peas with a charred slice of lemon.