For the pea and spinach risotto, melt the butter in a large pan until foaming, then fry the onion and garlic for 2-3 minutes, or until softened.
Add the rice and stir well to coat in the butter. Cook for a further 1-2 minutes, or until the rice is translucent. Add the wine and cook for 3-4 minutes, or until nearly all of the liquid has been absorbed. Meanwhile, keep the chicken stock hot in a pan set over a low heat.
Add a ladleful of the chicken stock to the rice and stir well. Cook for 1-2 minutes, or until nearly all of the stock has been absorbed, then stir in another ladleful of the stock. Repeat the process until the rice is cooked but still al dente. (You may not need all of the stock.)
Add the peas during the last 2-3 minutes of cooking, then stir in the baby spinach leaves, mascarpone and parmesan. Gently stir until the cheese has melted and the rice has a creamy texture. Season, to taste, with salt and freshly ground black pepper.
For the pea oil, bring a small pan of salted water to the boil, then add the peas and mint and blanch for 1-2 minutes. Drain and refresh under cold running water, then drain again and place the peas and mint into a food processor. Add the olive oil and blend to a smooth purée.
Pass the pea mixture through a fine sieve, pressing down lightly, into a small bowl. Discard the solids left behind in the sieve. Set the pea oil aside.
For the sea bream, season the sea bream fillets with a little salt. Heat a frying pan until hot and add the butter and olive oil. When the butter is foaming, add the sea bream fillets, skin-side down. Fry for 2-3 minutes, or until the skin is crisp and golden-brown. (The fish should be half-cooked at this stage.) Turn the fish over and cook for a further 1-2 minutes, or until the fish is completely cooked through (the flesh should be opaque all the way through and flake easily).
Spoon the risotto into the centre of four serving plates and top with the sea bream fillets. Dress the pea shoots with a spoonful of the pea oil and arrange a small pile on top of each piece of fish. Drizzle some more pea oil around the plates and serve.