Add the pasta to the boiling salted water and cook for 8 to 10 minutes, just until al dente. Meanwhile prepare onions, peppers, zucchini, tomatoes and place in large bowl Drain the pasta well and pour over vegetables. Mix...this will wilt the vegetables a bit. While it's still warm, toss the pasta with the salad dressing. Break up the tuna into smaller chunks and add it to the pasta with the vegetables and herbs. Toss gently. Let sit for 30 minutes for the flavours to blend. Better if it sits for an hour or more.