Heat 1 ½ tablespoons oil in a saucepan. Add rice and saffron and cook, stirring, until transparent. Add wine, stock, 60ml water and bay leaf. Bring to a boil. Add peas and beans and cook until rice has absorbed all the liquid. Remove from heat.
Combine rice, peas and beans in a large bowl. Whisk remaining 1 ½ tablespoons oil, lemon juice and vinegar until combined. Add salt and pepper to taste. Stir into rice mixture. Leave 1 hour in a cool place.
Chop capsicum in half and cut into dice. Pour boiling water over tomatoes, leave 2 minutes then plunge into iced water. Peel and dice. Mix capsicum and tomatoes into rice.
Cut chicken into thin strips and place in a bowl with half the garlic and 1 tablespoon lemon juice. Peel and clean prawns. Place in a bowl with remaining garlic, remaining 1 tablespoon lemon juice, 1 tablespoon olive oil, salt and pepper.
Heat 3 tablespoons oil in a heavy pan over high heat. Add chicken mixture; sear chicken quickly on all sides. Add prawn mixture and sear prawns on both sides. Reduce heat to medium. Cook another 5 minutes or until done. Arrange lettuce leaves on a large platter. Top with rice salad and chicken and prawn mixture. Garnish with lemon wedges.