Add yogurt to a cheese cloth and drain off excess water or whey. You will be left with thick yogurt. You can even hang it inside the refrigerator to make hung curd.
Wash and peel of the skin, if cannot just proceed.
Cut them to equal cube sized pieces, remove the moisture from them using disposable or absorbent tissues.
Mix all the marination ingredients and marinate for at least 2 to 12 hrs.
Soak the wooden skewers for at least 30 mins in water to prevent burning else you will have burnt skewers like mine.
Just before you begin to bake, cube the veggies and marinate in the left over marination. Veggies at room temp, using from the fridge right away makes them soggy. I do not marinate for long as tend to lose the crunch, so I marinate just before I bake them.
Remove the excess marinade and put them on to skewers, alternating veggies and fish. There will drippings from the meat while baking, do not forget to place a tray to collect the spills in case you use a wire rack for placing the skewers and not a tray. Otherwise it will mess up your oven.
Preheat the oven to 240 C, bake for 10 mins and then on 180 C for another 5 to 10 mins. I suggest you to check after 15 mins.In between you can baste the marinade to the tikkas to prevent them from drying.