In a mixing bowl, combine 2 big handfuls fresh cilantro leaves, finely chopped, 1/2 jalapeno, sliced, 1 tsp grated fresh ginger, 1 garlic clove, grated, 2 limes juiced, 2 tbsp soy sauce, Pinch sugar, sea salt & freshly ground pepper, and 2 tbsp of olive oil. Stir the ingredients together until well incorporated. Place a skillet over medium-high heat and coat with 2 tbsp of olive oil. Season the tuna generously with salt and pepper. Lay the tuna in the hot oil and sear for 1 minute on each side to form a slight crust. Pour 1/2 of the cilantro mixture into the pan to coat the fish. Serve the seared tuna with sliced avocado and the remaining cilantro sauce drizzled over the whole plate.