Cook pasta according to package directions. Drain pasta; rinse with cold water. Drain again.
Meanwhile, cook shrimp, uncovered, in boiling water for 1 to 3 minutes or until shrimp turn opaque, stirring occasionally. Drain shrimp; rinse with cold water. Drain again.
In a large mixing bowl combine pasta, shrimp, red or green sweet pepper, and green onions. Toss to mix.
For dressing, in a screw-top jar combine vinegar, oil, capers, dill or dillweed, garlic, salt, and pepper. Cover and shake well. Pour dressing over pasta mixture. Toss gently to coat. Cover and chill for 3 to 24 hours.
Just before serving, cut the pea pods in half crosswise. Stir pea pods into pasta mixture. If desired, serve on spinach- or lettuce-lined plates. Makes 4 main-dish servings.