Heat some oil in a large saucepan over medium-high heat. Add cumin seeds and button red chili and cook until fragrant, about 30 seconds.
Add coriander, turmeric, garam masala, and onion slices, and stir. Cook for 2 minutes until the onion is soft.
Add tomato and all the veggies and sauté for a few minutes.
Add the oats and stir to coat, cook the oats for a minute until oats are nice and toasty.
Add in water and stir. Cover and cook on low flame until oats is tender, about 10 minutes, string occasionally.
Season with salt to taste.