Make salmon: Prepare a medium-high fire in a gas or charcoal grill. Brush both sides of salmon with sesame oil. Sprinkle flesh side with rosemary and season with salt and pepper. Squeeze lemon over salmon; grill salmon until it flakes with a fork, 4 to 6 minutes per side.
While salmon is cooking, make relish: Combine tomatoes, olive oil, vinegar, basil, garlic and cumin in a small bowl. Season with salt and pepper and stir.
Serve salmon hot off the grill with relish on the side.