Place the peeled and cubed sweet potatoes, chopped onion, minced garlic, diced tomatoes (with their juice), tomato sauce, drained pinto beans, drained black beans, drained kidney beans, diced bell peppers, ground cumin, chili powder, smoked paprika (if using), crushed red pepper flakes, black pepper, and sea salt into the slow cooker. Stir everything together well to ensure the spices and vegetables are evenly distributed.

Set the slow cooker to high for 4-6 hours or on low for 6-8 hours. Allow the chili to cook until the sweet potatoes are completely soft and all the flavors have melded together. Stir once or twice throughout if you’re around, though it’s not strictly necessary. I like to check the sweet potatoes at the 4-hour mark on high to make sure they don’t get too mushy.

Once the sweet potatoes are fully softened and the chili is cooked to your liking, stir in the tomato paste to achieve your desired thickness. Start with 1/3 cup, and add a bit more if you want a thicker consistency. Allow the chili to sit for several minutes on the 'keep warm' setting so the paste can incorporate and the flavors can settle together.

Serve the chili hot, with optional toppings like shredded cheese, sliced avocado, or chopped cilantro, if desired. Leftovers taste even better the next day; store any remaining chili in an airtight container in the refrigerator for up to 5 days, or freeze for up to 3 months. I find that letting the chili sit for a bit before serving really helps the flavors come together.