Heat oil in a skillet over medium-high. Add pork and spread flat and let it sit 2 minutes until the bottom darkens and caramelizes. Break apart and cook until crispy-edged throughout, 2–3 more minutes. Add garlic and soy sauce, toss, and remove from heat. Set pork aside.
Build the Sauce in the Pan
Reduce heat to medium-low. Add tahini, chili oil, soy sauce, black vinegar, sesame oil, and sugar directly to the pan. Add 1/4 cup of water gradually, stirring until the sauce is smooth and pourable.
Cook the Noodles
Boil noodles according to package and drain well.
Toss
Add noodles directly to the sauce and toss until every strand is fully coated. Add a splash of water if it tightens too fast.
Plate and Finish
Mound noodles in a deep bowl. Spoon crispy pork over the top and finish with scallions, sesame seeds, and a heavy chili oil drizzle.