Cook pasta to desired doneness as directed on package, adding peas during last 5 minutes of cooking time. Drain; rinse with cold water to cool.
In very large bowl, combine cooked pasta and peas, tuna and pimientos; mix well.
In food processor bowl with metal blade, combine all remaining ingredients; process 2 to 3 minutes or until mixture is creamy and feta is finely chopped. Add to pasta mixture; mix well to coat. Serve immediately, or cover and refrigerate until serving time.