Begin by cooking the pasta according to the package directions – boil for 7-10 minutes or until al dente. Drain the pasta in a colander.
While the pasta water is heating up, slice the sausage into medallions, 1/2 inch thick. Cook the sausage in a large skillet over medium heat until it is well browned. Drain on a plate lined with paper towels.
While the pasta and sausage are cooking, thinly slice the bell peppers, onion, and celery. Place the vegetables in a very large bowl. (While you’re at it, wash and slice the rest of the celery and freeze for use in a soup on another day)
After the pasta and sausage finish cooking, allow them to cool slightly. While they are cooling, make the vinaigrette. Whisk together the oil, vinegar, mustard, garlic, salt, cayenne, paprika, and black pepper.
Place the slightly cooled pasta in the bowl with the vegetables (don’t worry if it’s slightly stuck together, the vinaigrette will loosen it. Don’t use water!). Add the cooked sausage, pour the vinaigrette over everything and stir to coat. Roughly chop 1/3 bunch of parsley and add it to the salad, stirring again until evenly mixed in. Serve warm or cold!