First make the Jalapeño Vinaigrette: Place the jalapeño, yuzu juice, sugar, and olive oil in a blender and blend until smooth; chill in the refrigerator until ready to use.
Clean the bay scallops by removing the side muscle (abductor muscle) and rinsing them under cool water. Pat them dry with paper towels and cut them into 1/4-inch dice. Put the scallops in a medium bowl and toss them with the Thai chile, 2 teaspoons of the salt, and 2 tablespoons of the olive oil; mix well.
Peel the banana and cut it into 1⁄4-inch dice. Put it in a small bowl and add the remaining teaspoon of salt, the remaining 2 tablespoons of olive oil, and the sugar. Mix gently to combine but try to retain the texture and shape of the banana.
Put a spoonful of the banana mixture on each serving plate. Top with a generous spoonful of the scallops, a sprinkling of pepper, and a few dill sprigs. To serve, drizzle the vinaigrette around the bed of tartare.