Mix onion, chile, garlic, lime juice, arugula, salt, and pepper. Add zucchini and tomatoes. Let marinate for 10 minutes to 1 hour. Use a slotted spoon to remove any extra liquid. Whisk together the dressing ingredients and toss. Serve with a slotted spoon as zucchini will continue to release extra, unwanted moisture.
Recipe note: This is great served with simply grilled meats such as Tequila Marinated Pork Tenderloin.