Place cucumber slices in a colander in the sink. Sprinkle salt on top and toss to coat. Allow to sit for 20 minutes. Rinse cucumber slices very well with cold water; drain.

Mix rice vinegar, 1 tablespoon soy sauce, 2 teaspoons sugar, and sesame oil together in a bowl. Add cucumber slices and sesame seeds. Toss gently and transfer to the refrigerator.

Whisk 3 tablespoons soy sauce, mirin, sake, and 2 tablespoons sugar in a small bowl to make teriyaki sauce.

Heat oil in a large skillet over medium-high heat. Prick chicken skin all over with a fork; place skin-side down in the hot oil. Cook until the skin is golden brown, about 12 minutes. Flip and continue cooking until second side is browned, about 7 minutes.

Reduce heat to medium; pour teriyaki sauce over chicken. Cook until sauce thickens, about 2 minutes. Remove from heat. Cover and let rest for 5 minutes. Slice chicken into strips and place in a bowl; add teriyaki sauce from the skillet and toss to coat.

Toast corn tortillas in a large, dry skillet over medium-high heat until crisp and slightly blackened around the edges, 1 to 2 minutes per side. Wrap in a dish towel to keep warm.

Mix sour cream and sriracha sauce together in a small bowl.

Divide teriyaki chicken among tortillas. Drizzle sour cream-sriracha mixture over chicken. Top with cucumber salad, scallions, and black sesame seeds.