1. In a food processor, combine the walnuts, spinach, basil, cheese, garlic, 1 tbsp olive oil, and salt to make the pesto. Process about 1 minute until smooth.
2. Add broth and process 15 to 20 seconds. Transfer mixture to a small saucepan. Set aside.
3. Spray a large skillet with nonstick cooking spray. Place the skillet over medium-high heat and add 2 tsp olive oil. When oil is hot, add tuna steaks and cook 3 to 5 minutes on each side or until cooked through.
4. Over low heat, warm the pesto in the saucepan.
5. Serve tuna steaks with quinoa and top with pesto and tomatoes.
Makes 4 servings.