Sweet Potato Cauliflower Curry

0 Preheat oven to 420 F. Chop cauliflower into bite size pieces. Toss in 1 tbsp of olive oil. Place on sheet pan, and roast for 15 minutes. 
2 While cauliflower is roasting add 1 tbsp of olive oil to a large nonstick skillet and heat over medium-high heat. Add the onion and ginger and cook for 4 minutes.
4 Stir in the coriander seeds, cumin seeds, turmeric, cayenne if using, and salt and toast for 15 seconds. Then add the tomatoes and sweet potatoes, and cook until they are tender, about 12 to 15 minutes.
6 Remove cauliflower from oven and add to the pot stirring well to combine.