How to Make It
Cook the spaghetti according to the package directions. Drain the pasta, rinse under cold water, and return it to the pot.
Heat the oil and red pepper in a large skillet over medium heat until the pepper is sizzling, 2 to 3 minutes.
Remove from heat and stir in the chopped scallions, tahini, vinegar, soy sauce, 3 tablespoons water, and ½ teaspoon salt.
Add the tahini sauce to the pasta and toss to coat.
Serve topped with the sesame seeds and sliced scallions.