Put 15 skewers into a shallow baking dish that they can lay flat in. Fill with water and allow to soak for at least 30 minutes.
Trim the zucchini and cut in half. Slice into half moons about 1/2" thick.
Trim the onion, cut the half in half, and then cut into slices about 1/2" wide. Top the peppers and cut into squares about 1"x1".
Seed the mango and cut into 3/4" squares, do the same with the pineapple.
Put all sauce ingredients into a small jar with a lid and shake vigorously until combined.
Alternating veggies, thread them onto the soaked skewers, using each veggie at least one time on each skewer. Make sure to pierce the veggies right through the middle so that they stay firmly in place. (If you have leftover veggies use them in a stir fry the next day!)
Heat a grill to medium heat. Place the skewers across the grate and brush with the sauce mixture. Close the grill and allow to cook for about 5 -7 minutes. Flip the skewers over with a tongs, and brush the other side with the sauce. Cook with the grill open for another 5 - 7 minutes (depending on you preferred level of 'bite' and then remove from grill. Enjoy!