Cut potatoes into 1.5" to 2" wedges. Soak in water for 5 minutes. Drain water and pat-dry potato pieces very well.

Heat oil at medium heat. Deep-fry sweet potatoes for 5 minutes and remove from oil. Then turn oil to high heat, put potatoes back in the hot oil and cook for a minute longer, until just turning in color. Remove from oil.

In a frying pan, heat sugar, Mirin, honey, and Soy Sauce at medium heat until slightly thickened. Add cooked sweet potatoes in the sauce and cook for 2-3 minutes, coating with the sauce which is further thickened but still fluid. Separate the coated potato pieces on a sheet lined with a silicon mat or oiled parchment paper so that they don't stick together. Sprinkle with black sesame seeds. Cool for a few minutes and serve.