Cook pasta according to package directions; drain and rinse under cold water.
While pasta is cooking, put broccoli in a steamer basket over a large pot of boiling water and steam for 3 minutes; add in snow peas and sugar snap peas; steam for 2 minutes more, until all the vegetables are crisp tender.
Toast the peanuts in a small dry skillet over med-high heat until fragrant, 3-5 minutes, stirring often; set aside to cool.
Make the sauce by pureeing the peanut butter, soy sauce, water, vinegar, lime juice, scallion, ginger, brown sugar, and red pepper in a food processor or blender until smooth.
Just before serving, toss the pasta with ¾ cup of the sauce; divide between 6 serving bowls and top each serving with the vegetables.
Drizzle remaining sauce over the vegetables; coarsely chop the peanuts; sprinkle them on top; serve.