Combine all the ingredients for the salsa in a medium bowl, season to taste with sea salt and freshly ground black pepper, and combine well.
2 avocados, 3 plum tomatoes, 1 red onion, 1 jalapeno pepper, 2 tbsp. lime juice, 2 tbsp. fresh cilantro, Sea salt and freshly ground black pepper
Refrigerate the salsa for 2 to 4 hours to bring out the flavors.
Preheat your grill to medium-high heat.
Sprinkle coriander over the tuna steaks and season to taste with sea salt and black pepper.
4 6 oz. pieces fresh tuna, ½ tsp. ground coriander, Sea salt and freshly ground pepper to taste
Grill the tuna for 2 to 3 minutes per side.
Serve the grilled tuna with the avocado salsa on top.