In a small bowl, whisk the sauce ingredients until combined. The sauce will separate a little due to the sesame oil, but it is fine, whisk until most of it is combined. Set aside.
In a medium or large pot, heat up about 4 cups of cold water, and once simmering, add in the ramen noodles. Discard the seasoning packet for next time. Remove from heat and let the noodles soften for about 2 minutes. Rinse and drain, leaving about 1 cup of noodle water for later.
Meanwhile, heat some cooking oil over medium-high heat in a wok pan or large skillet. Once the oil is very hot and sizzling in the frying pan, stir-fry the mushrooms for 2 minutes first, and then add the remaining veggies, cook for 2 minutes.
Follow with garlic, and ginger. Cook until just fragrant.
Lower the heat and pour in the sauce. Stir until veggies are coated and the sauce has thickened slightly. Stir in the noodles and mix to combine. If needed, add more ramen cooking water.
Serve ramen stir fry right away in soup bowls with freshly sliced scallions, sesame seeds, and more red chili flakes.