Inspired from a recipe at Food.com.
Turn your oven to 400.
Place potatoes and cauliflower florets into a large bowl and shake as you drizzle with your oil to get them evenly covered. In a small bowl, mix together all your spices. This spice blend is just a recommendation, too-- use whatever you prefer (turmeric, garam masala, ground coriander or go for a different blend altogether.) Shake about 1/3 of the spices over the cauliflower and potatoes, then shake the bowl and repeat till you've used up all your spices.
Spread the cauliflower and potatoes in an even layer on two baking sheets-- making sure they aren't too crowded so they roast evenly.
Set a time for 20 minutes, then toss and rotate the pans in the oven. Roast 10-15 more minutes, making sure not to burn.
Serve warm as is, or as a side dish for a larger meal.