2 boneless, skinless chicken breasts
4 teaspoons peanut or canola oil, divided
2 cloves garlic, minced
1 1/2 inch piece of ginger, peeled and minced
1 pound spaghetti or soba noodles
1 English (seedless) cucumber
5 scallions (white and light green parts) chopped
2 teaspoons black sesame seeds (toasted white ones would be fine, too)

For the sauce:
2 tablespoons natural peanut butter*
2 tablespoons rice vinegar
3 tablespoons sesame oil
2 tablespoons soy sauce
1 tablespoon sugar
1/2 teaspoon red pepper flakes