Hot-and-Sour Peanutty Noodles with Bok Choy

INGREDIENTS

• 2 tablespoons low-sodium soy sauce
• 1 large shallot, sliced
• 1 piece (about 1 inch) ginger, peeled and finely chopped
• 1/4 teaspoon red pepper flakes (or more to taste)
• 3/4 cup low-sodium vegetable stock or water
• 1 tablespoon dark sesame oil
• 2 1/4 teaspoons kosher salt, divided
• 1 tablespoon canola or sunflower oil
• 1/2 cup chopped unsalted roasted peanuts
• 1 tablespoon rice vinegar
• 1 pound baby bok choy, leaves and stems separated, roughly chopped
• 1 red bell pepper, sliced
• 8 ounces whole-wheat spaghetti