Place the scallops in a non-metallic bowl and mix with the lemon juice. Cover the bowl with
cling film and chill for 15 minutes.
Melt 2 tablespoons of the butter with the oil in a deep saucepan over a medium heat. Add the
onion and cook, stirring occasionally, until soft and starting to turn golden. Add the rice and mix
to coat in oil and butter. Cook, stirring, until the grains are translucent. Dissolve the saffron
in 4 tablespoons of hot stock and add to the rice. Gradually add the remaining stock a ladleful at
a time, stirring constantly, until all the liquid is absorbed and the rice is creamy. Season with
salt and pepper.
When the risotto is nearly cooked, preheat a griddle pan over a high heat. Brush the scallops
with oil and sear on the griddle pan for 3-4 minutes on each side, depending on their thickness.
Take care not to overcook or they will be rubbery.
Remove the risotto from the heat and add the remaining butter. Mix well, then stir in the
Parmesan until it melts. Season with lemon juice, adding just 1 teaspoon at a time and tasting as
you go. Serve the risotto immediately with the scallops and lemon wedges arranged on top, sprinkled
with lemon zest.