Measure out all the sauce ingredients and combine. (Mustard, balsamic vinegar, mayonnaise, sake, soy sauce.)
Cut the chicken and the potato into bite-sized pieces. Finely chop the garlic.
Put the potatoes in a heatproof container and microwave until soft. In our microwave oven it's 2 minutes first, one stir, and then another 1 minute.
Put the garlic and olive oil in a frying pan and cook over low heat, taking care not to let the garlic burn, for about 5 minute or until it bubbles, to slowly draw out the fragrance.
Add the sautéed garlic to the sauce from Step 1. If there's a little olive oil there too, no problem.
Don't clean out the pan; put the chicken in skin side down and cook over high heat for 3 minutes, then turn over and cook over medium heat for another 3 minutes. When the chicken is browned, add the potato.
Swoosh the sauce from step 5 into the pan. Shake the pan a bit and it's done. Don't move things about too much after adding the sauce.
If you pile it up high on the serving plate it'll look more enticing. Pour the sauce over to finish.
Story Behind this Recipe
This recipe is requested a lot by my friends. I've finally written it down as a proper recipe.
Sauté the garlic slowly so that the flavor is transferred to the oil. Fry the chicken very well, to the point where you think it's almost burned. The mustard sauce can be used for pork, fish and so on too.