In a saute pan, heat the butter or coconut oil over medium heat. Add the diced onion and garlic, and saute for about 5 minutes, until tender. (You can do this while your sweet potato chunks are steaming!)
Transfer the onions, garlic and sweet potato chunks into a blender, and add the rest of the ingredients. Blend well, scraping down the sides, until everything is creamy. Adjust seasonings to taste and set aside-- this is your curry sauce.
In a separate pot, saute any veggies you like until they are nearly tender. (I included sweet potatoes, broccoli, zucchini, carrots, and onion.)
Once your veggies are nearly cooked, pour the curry sauce over them.
Bring the sauce to a simmer, then reduce the heat and cover, to let the flavors blend for about 5-10 minutes. Your veggies will be nice and tender, while packing a huge punch of flavor!
The best part of curry dishes, if you ask me, is eating it the sauce with rice, so even if you're not eating grains, you can still enjoy this curry sauce over a bed of cauliflower "rice!" (Simply pulse raw cauliflower in a food processor, until you have a rice-like texture.) Pour the curried vegetables over the rice and serve warm.