Heat olive oil in a large, heavy-bottomed pan over medium-low heat. Cook the onion and garlic until soft, about 5 minutes. Stir in the rice, and cook for 5 minutes more, stirring frequently.
Pour in 350ml of the chicken stock, and bring to boil over high heat, stirring occasionally. Reduce heat to medium-low, and simmer, uncovered for 5 minutes, continuing to stir. Pour in the remaining chicken stock and wine, increase heat to medium, and cook for about 5 more minutes, stirring constantly.
Add the scallops, prawns, peas and red pepper. Cook, stirring constantly, until the remaining liquid is almost absorbed, and the seafood has cooked, about 5 minutes. When the rice is just tender and slightly creamy, season with Parmesan cheese, basil, lemon juice and pepper.