In a pot of heavily salted water, boil the tortellini according to package directions. Drain into a colander and shake dry. Add the red onion to the colander and rinse the pasta and onion under cold water until the pasta is cool. Shake dry. Dry the pot and return the tortellini and onion to it.

Add the peppers, salami, oil and vinegar and stir to combine. Season to taste with salt, black pepper and crushed red pepper until the salad is flavorful. Stir in the arugula. (If making ahead, pack the arugula on top of the pasta in an airtight container, refrigerate for up to 3 days, then stir to combine.)