- In a large pot of salted boiling water, cook the rapini for about 2 minutes or until al dente. Submerge in ice water and drain thoroughly. Cut into large pieces.
- In a bowl, toss the rapini and kidney beans in 2 tbsp of the lemon juice and 2 tbsp of the oil. Set aside.
- Preheat the grill, setting the burners to high. Oil the grate.
- In another bowl, toss the chicken breasts with the remaining lemon juice and oil and the spices. Season with salt and pepper. Coat thoroughly, then let marinate for 5 minutes. On a large plate, lightly oil the tomato and onion pieces.
- Grill the chicken pieces for about 4 minutes on each side or until they are thoroughly cooked. Grill the tomatoes and onions for 6 minutes or until tender. Add the tomatoes and onions to the rapini and kidney beans. Toss gently and season with salt and pepper.
- In a large serving dish, place the vegetables and beans, then top with the chicken and bocconcini if desired.