Add Olive Oil (1 tablespoon) to a skillet over medium heat. When hot, add and sauté Red Onion (1), Garlic (3 clove), and Bell Pepper (2) for 3-5 minutes. Once cooked, transfer to the slow cooker.
Add the Chili Powder (2 tablespoon), Ground Cumin (1 tablespoon), Chickpeas (1 can), Red Kidney Beans (1 can), Fire Roasted Diced Tomatoes (1 can), Vegetable Broth (2/3 cup), Zucchini (1/2 cup), Chipotle Peppers in Adobo Sauce (3 tablespoon), and Tomato Paste (4 tablespoon) to the slow cooker. Cook on high for 90 minutes or low for 3 hours.
Instant pot option: Add onion, garlic, bell peppers, and oil to the instant pot. Press sauté option and cook for 3-5 minutes (stirring) or until onion and peppers are softened. Turn off sauté. Add the remaining ingredients (minus salt and pepper + toppings) to the instant pot. Stir to combine. Secure with lid and press manual cook (sealed) for 20 minutes followed by slow release.
After the chili has been cooked by either method, stir in Kosher Salt (1 teaspoon) and Ground Black Pepper (to taste) and serve with toppings of choice. Ex: Fresh Cilantro (to taste), Shredded Cheese (to taste), and Jalapeño Pepper (to taste).