Cut chicken into 1" cubes and place in a shallow container. I use a Ziploc bag in a bowl. A flat pyrex/glass dish would work as well.
Combine the next six ingredients and pour over the chicken, tossing to coat completely.
Put into the refrigerator to marinate 2 to 8 hours.
While the chicken is marinating, wash and cut the vegetables into approximately 1" pieces (similar to the chicken pieces). The onions do well cut into wedges with a bit of the tail end left on. If the mushrooms are much bigger, cut down to make uniform.`
If using wooden/bamboo skewers, soak in water at least 30 minutes to prevent flaming tips.
Prepare your grill to medium-high.
Skewer chicken and vegetables snugly together but not smashed together: chicken/pepper/chicken/onion/chicken/zucchini/chicken/mushroom or whatever order suits you.
Toss the vegetables (separate or together doesn't matter) in a few tbsp of olive oil and sprinkle with salt and pepper.
Grill over direct flame until the chicken at the center reaches 165F, turning every few minutes. Can take anywhere from 8-15 minutes depending on size of chicken chunks and temperature of the coals/gas.
To complete our table, we serve with saffron (or turmeric) yellow rice and a green salad.