Seared Ahi Tuna with Amazing Sauce

Serves 4

Adapted from Simply Recipes

1/2 cup chopped fresh cilantro leaves
1 jalapeño, seeded, de-ribbed, minced
4 teaspoons fresh ginger, peeled and grated (use a microplane grater)
4 garlic cloves, grated
Juice of 4 limes
1/3 cup soy sauce
1/4 teaspoon sugar
Salt and freshly ground black pepper
1/4 cup plus 2 tablespoons extra-virgin olive oil
4 (6 ounce) blocks high-quality tuna*