In a bowl place the lager and flour, whisk together so there are no lumps. It should be a similar consistency to double cream, if necessary add some more flour. Add the turmeric, salt and pepper and bicarbonate of soda. Leave the batter to rest in the fridge for around 30 minutes.
Boil the peas in water, adding the vegetable stock and a pinch of salt. In a separate pan, boil the cream and crushed garlic and allow the flavours to infuse. Once the peas are cooked, drain the liquid from them. Place a handful of mint in a food processor and blitz.
Add 3/4 of the peas to the food processor, keeping the others aside for later. Blend them to get a puree consistency and add the cream and combine. Add the final peas and blitz, do not allow the peas to become completely broken down to allow some texture in the mushy peas.
Lightly score the fish and dip it in the batter, tap the fish on the side of the pan to remove any excess batter. Going away from yourself, place the fish in the pre-heated oil and allow to fry until the fish is golden brown and floats.
Serve up with the mushy peas, chips, tartar sauce and a wedge of lemon.