Cut the salmon into cubes, slice the zucchini, and dice the onion.
Prepare the marinade. In a small bowl, combine olive oil, lemon zest and juice, garlic, oregano, thyme, chili, cumin, salt, and pepper. Add the salmon pieces, zucchini, and onion to the mixture. Leave for about 30 minutes or cover and refrigerate for about an hour.
Thread the marinated salmon and vegetables onto skewers. If using wooden or bamboo skewers, pre-soak them in water.