In a small dry frying pan over medium heat, toast 2 tsp sesame seeds, stirring often, until fragrant and beginning to brown, 2-5 min. Pour onto a small plate to cool. Cut 1 lb sushi-grade tuna into a 1/4-inch (6-mm.) cubes and place in a bowl. Add 3/4 tsp peeled and minced fresh ginger, 1 1/2 tbsp soy sauce, 2 1/4 tsp fresh lime juice, 1 jalapeno minced and 1 1/2 tbsp sesame oil and stir gently to combine. To serve, divide the tuna among individual bowls or plates and sprinkle the sesame seeds on top, dividing them evenly. Top with fresh chives and serve. Serves 4.