Preheat the oven to 425 F. Cut the cauliflower into medium florets and cut the potatoes into ¼-inch thick semicircles. Arrange on two separate sheets. Toss with a drizzle of oil, salt, and pepper. Roast for about 20 minutes, with the cauliflower on the middle rack and the potatoes on a lower rack.
For a non-oven method: Heat 1 tbsp avocado oil in a pan over medium heat. Cook the cauliflower in batches until it is soft and cooked, but still has a crunch to it. Do the same with the potatoes or just add the potatoes with the second cauliflower batch and hope it works out, which is what I usually do.
While the veggies roast, make the flavor base. Heat oil in a pan. When the oil is hot, add cumin seeds and let them sizzle for a minute or so before adding hing. Add onions and cook until translucent, about 5 minutes.
Add ginger, garlic, and green chilis. Cook for 2-3 minutes.
Add tomatoes and salt. Stir until the tomatoes clump together and are well-combined with everything. Add the rest of the spices and stir for a couple minutes.
Toss the cauliflower and potatoes in. Stir for a few minutes. Add the chickpeas and a splash of water. Reduce heat to low, cover, and simmer for about 5 minutes. It may take a little longer if you're using canned chickpeas and want them to be softer!
Serve with rotis or a flatbread of your choice.