Miso Noodles with Seared Ahi Tuna

Name: Miso Noodles with Seared Ahi Tuna
Ingredients: 1/2 cup white miso paste; 3 teaspoons low-sodium soy sauce; 2 tablespoons mirin; 2 tablespoons canola oil; 2 tablespoons seasoned rice vinegar; 1 teaspoon sesame oil; Kosher salt; 10 ounces sugar snap peas, julienned into matchsticks; 12 ounces buckwheat soba noodles; 2 medium organic carrots, peeled and julienned into matchsticks; 2 tablespoons canola oil, plus more for brushing; 1 tablespoon sweet soy sauce; 2 teaspoons yuzu; 1 teaspoon grated fresh ginger; 3 pounds good-quality ahi (or yellowfin) tuna, sushi-grade if possible; 1/4 cup black sesame seeds; 1/4 cup white sesame seeds; 4 scallions, thinly sliced on the bias, for garnish; Special equipment: 8 bamboo skewers soaked in water for 10 to 15 minutes