Step 1
In a 9- by 13-inch baking dish, whisk collectively the oil, soy sauce, yuzu kosho, sansho pepper, salt, and garlic. Add the tomatoes and toss to coat, then organize lower facet down within the dish. Put aside to marinate at room temperature for quarter-hour.
Step 2
Warmth a charcoal or gasoline grill to excessive, then financial institution the coals or flip off the burner on one facet. Add the tomatoes lower facet right down to the most popular a part of the grill, reserving the marinade, and prepare dinner till barely charred, 2–4 minutes. Utilizing tongs, flip the tomatoes, then spoon the reserved marinade over the tops and proceed grilling with out flipping till the tomatoes are barely caramelized, 6–8 minutes. Garnish with mitsuba and serve.
