Lighter Sesame Noodles

INGREDIENTS

• Coarse salt
• 12 ounces whole-wheat spaghetti
• 1 bunch broccoli, cut into florets, stalks peeled and thinly sliced
• 2 red bell peppers (ribs and seeds removed), thinly sliced
• 1 large onion, halved and thinly sliced
• 1/4 cup creamy peanut butter
• 3 tablespoons dark-brown sugar
• 2 tablespoons rice vinegar
• 2 tablespoons soy sauce
• 1 tablespoon toasted sesame oil
• 2 garlic cloves, minced
• 1/2 to 1 teaspoon red-pepper flakes