Sorry about the lame measurements, I don't really measure when I'm making up a recipe (oops).
So I started by peeling the zucchini because I wanted them to get really soft and sort of melt-in-your-mouth texture. Chopped them into little pieces (cut them long-ways twice so when you slice them you get little triangle pieces). Also chop the mushrooms up in little pieces.
Put those in a skillet with the oil on med-low while slicing up the onion (I like them a little big), and dice the garlic. Add in with the zucchini, and added the spices...I actually saved the salt and black pepper till later.
Turned up the heat some and stir.
After everything starts to get all juicy, add the rice and mix it in. Cook it a while longer before adding the tomatoes. You might want to keep the juice out if you don't want it to be liquidy.
Mix it together again, add some salt and pepper..maybe some more garlic powder. Lower the heat, put a lid on it and cook it (stirring now and again) until you think it's time to eat it (haha).
Some things I might try to change it up: add vegan cheese..also some faux meat like burger-style crumbles or maybe some veggie sausage in place of the rice or just added to it.