Bring a large pot of lightly salted water to a boil. Cook pasta until tender with a bite, 9 to 11 minutes, or according to package directions. Reserve ½ cup cooking water; drain.
To make the peanut sauce: Whisk together peanut butter, soy sauce, maple syrup, lemon juice, 2 teaspoons Sriracha, ginger, and 2 tablespoons reserved cooking water.
Heat oil over medium-high heat in a very large skillet. Add onion and bell pepper. Cook and stir until softened, 4 minutes. Add shrimp and peas. Cook and stir until shrimp is opaque, 3 to 4 minutes.
Add pasta and peanut sauce to skillet. Toss to combine. Cook until heated through, 1 to 2 minutes, adding additional pasta water as needed to reach desired sauce consistency. Garnish with cilantro and/or sesame seeds. Serve with Sriracha.
