Place swordfish in a non-reactive container. Whisk together zest, olive oil, coriander, herbs and salt. Pour marinade over swordfish and let marinate in refrigerator for 8 hours. Cut peppers and onions into 1-inch squares. Skewer your ingredients rotating them 1 at time, first the swordfish, then a pepper square, followed by a chunk of onion, and a cherry tomato. Brush with marinade and grill for about 2 minutes on each side.