Sprinkle the potatoes and cauliflower with the salt
Arrange the vegetables on lined baking sheets in a single layer and roast at 400° until the potatoes are fork tender and the vegetables have browned, about 20 minutes.
Meanwhile, in a large skillet cook the garlic, ginger and onion over medium heat using a bit of water to keep it from sticking.
Stir in the spices and tomatoes with the juice from the can.
Stir in the spices and tomatoes with the juice from the can. Reduce the heat and let this sauce simmer until the potatoes and cauliflower are done, then combine the vegetables with the sauce.