Add olive oil to the pan on medium-high heat.
When the pan is hot, continue adding chopped garlic and slices of ginger and cook until lightly turn brown (but not burn). This step will bring up the flavor of fresh garlic and ginger.
Add soy sauce, mirin, sugar to the pan and bring to a simmer, stirring all the while until the sauce thickens.
Adjust seasoning to taste then turn off the heat.