Cut tofu into cubes (1/2 - 1 inch thick).
Cut peppers and zucchini into bite-size pieces (1/2 - 1 inch long).
Combine remaining marinade ingredients (ground coriander, garlic powder, ground ginger and tamari) into a bowl and mix well.
Place tofu, peppers and zucchini in a wide container, preferably with a lid and pour marinade over, ensuring all pieces are immersed.
Marinate overnight, or a minimum of 1 hour.
Add tofu, peppers and zucchini to skewers, alternating for a variety of veggies.