Preparation

• Heat a grill pan over medium-high heat or prepare a medium-high (400°F) gas or charcoal grill fire.
• Combine the tomatoes, olives, and capers in a medium bowl. Heat 2 tsp. of the oil in a 10-inch skillet over medium heat. Add the garlic and cook, stirring occasionally, just until fragrant, about 10 seconds. Add the red pepper flakes and sugar, and stir in the tomato mixture and basil. Season to taste with salt and pepper, and take off the heat.
• Brush both sides of the tuna with the remaining 2 tsp. oil and season with salt and pepper. Grill until rare to medium rare in the center, 2 to 3 minutes per side. Slice the tuna into thick slices and serve topped with the salsa.