Cut the mangos in half, using the tip of your knife to cut around the large seed in the center. With the knife tip make slashes in the pulp of the fruit but not through the skin. Cut again in the other direction so that you've made hash marks in the fruit. Now turn the skin of the fruit inside out so that the fruit projects outward. With a spoon scoop out the already cut fruit into a mixing bowl.
Peel the onion, cut in two and slice from root end to stem end into a fine julienne. Mix the mango and onion together.
Combine the honey, lime juice, mint and soy in a small bowl. Pour this vinaigrette over the mango and onion and serve.