The creamy cannellini beans, the crunchy cucumber, and the tangy dressing make for a refreshing meal.
Heat a large nonstick grill pan over medium-high heat.
Combine the first 6 ingredients, 1/4 teaspoon salt, and 1/8 teaspoon pepper. Sprinkle tuna with 1/4 teaspoon salt and 1/8 teaspoon pepper. Coat pan with cooking spray. Add tuna to pan; cook 3 minutes on each side or until desired degree of doneness. Slice tuna; serve over bean salad. Serve with lemon wedges.