1. Brown the Beef: In a large, heavy-bottomed pot or Dutch oven, heat over medium heat. Add the lean ground beef, breaking it apart with a wooden spoon as it cooks. Continue until fully browned and no pink remains. Drain any excess fat.
2. Sauté the Veggies: Stir in the diced onion, chopped green bell peppers, celery, and mushrooms into the pot. Cook for about 5-7 minutes, stirring occasionally, until they soften and release their wonderful aromas.
3. Add Tomatoes & Liquids: Pour in the undrained diced tomatoes, undrained stewed tomatoes with Italian seasoning, tomato sauce, and water. Give everything a good stir until all ingredients are well combined.
4. Season & Mix in Proteins: Sprinkle in the chili powder, generous amounts of sea salt, and black pepper. If you enjoy a little extra kick, now's the time to add the optional cayenne pepper. Stir in the shredded rotisserie chicken, along with the rinsed and drained kidney beans and pinto beans.
5. Simmer to Perfection: Bring the chili to a gentle boil, then immediately reduce the heat to a low simmer. Let it cook uncovered for at least one hour, stirring occasionally to ensure the flavors deepen and the chili thickens beautifully.
6. Taste & Serve: Taste the chili and adjust any seasonings if needed. Ladle the hot, hearty chili into serving bowls. For a fresh summer touch, garnish with optional toppings like a dollop of plain Greek yogurt or a sprinkle of fresh cilantro!