Dice the onion, bell pepper, and celery into 1/2-inch pieces. This prep work is essential to do first so all components are ready when you need to assemble the chili. Uniform sizing helps everything cook evenly in the slow cooker.

Add the diced vegetables, drained and rinsed pinto beans, frozen corn, diced tomatoes, tomato sauce, and Rotel tomatoes to your slow cooker. Pour in the vegetable stock and lime juice. In a small bowl, whisk together the chili powder, cumin, smoked paprika, cayenne pepper, and salt, then stir this spice mixture directly into the slow cooker until well combined. I prefer freshly ground chili powder here—it makes a noticeable difference in depth of flavor compared to older spice jar versions.

Cover the slow cooker and cook on the low setting for 6 hours. The long, gentle cooking allows all the flavors to meld together beautifully and lets the vegetables become tender. If you're freezing this for later, let it cool to room temperature before transferring to a freezer-safe container—it will keep for up to 3 months frozen.

Ladle the chili into bowls and serve with your choice of toppings. Common options include shredded cheese, sour cream, diced onions, jalapeños, crushed tortilla chips, or fresh cilantro.