Unwrap ramen noodles and discard seasoning packet; set aside.
In a small bowl, mix cornstarch and 2 Tbsp. water; set aside.
In a small pot, whisk all sauce ingredients together. Bring to a boil, then reduce heat to low. Stir in cornstarch-water mixture. Simmer and stir until thickened, 2-3 minutes. Mixture should coat the back of a spoon. Feel free to adjust seasonings to your preference. Remove from heat and cover; set aside.
In a medium pot set to high heat, boil 6 cups water. Stir in ramen noodles. Cook noodles for about 2 minutes, until still chewy. They will continue cooking in the sauce once combined.
Drain noodles and return to pot. Pour sauce over noodles and mix to coat well.
Set pot to medium-high heat and cook noodles in sauce, until sauce is slightly absorbed and noodles are tender, about 3 minutes.
Garnish with sesame seeds and chopped scallions, if desired.