Whisk chile, garlic, vinegar, soy sauce, vegetable oil, peanut butter, sesame oil, ginger, and 1 tsp. salt in a large bowl. Add snow peas and toss to combine.
Cook udon in a large pot of boiling salted water according to package directions. Add shrimp 3 minutes before noodles are done and cook, stirring occasionally, until shrimp are pink and cooked through. Drain noodles and shrimp and add to dressing; stir vigorously to combine.
Transfer noodle mixture to a serving bowl or platter. Top with peanuts and cilantro. Serve immediately or at room temperature.
