In a food processor, combine the lemon juice, olive oil, 1 cup of the basil leaves, 1 garlic clove, 1/2 teaspoon of the salt ,and 1/4 teaspoon of the black pepper. Puree until smooth; set aside.
Heat a grill to medium high and mist with cooking spray. Halve one garlic clove and rub the steaks with its cut sides. Season meat with 1/4 teaspoon each of the salt and black pepper. Grill 5 to 6 minutes a side.
Mince remaining garlic and saute in pan coated with nonstick spray over medium-low heat for 2 minutes; let cool slightly. In a medium bowl, combine the white beans, tomatoes, red onion, remaining salt and black pepper, and sauteed garlic. Tear up remaining basil and combine with bean mixture.
Divide beans among four plates and top with steak. Add basil puree and serve.