1/2 cup ponzu
1/4 cup mirin
4 teaspoons soy sauce
2 teaspoons grated ginger
Sambal oelek (an Asian chili paste)
2 hamachi collars (about 1/2 pound each)
Vegetable oil, for brushing
One 2-inch piece daikon radish, peeled and finely grated
2 or 3 shiso leaves, chopped, optional