Heat the oil in a large stockpot or Dutch oven (5-6 quart) over medium heat. Add the onion, peppers, garlic and ¾ teaspoon salt and stir. Cook, stirring occasionally, until the onions are tender and translucent, about 8-10 minutes.
While the vegetables cook, in a small bowl add the chili powder, cumin, coriander, paprika and chipotle. Stir with a spoon until blended.
Use the spatula to scoot the vegetables to the outer edge of the pot. Add the tomato paste to the center of the pot and let it cook only in the center of the pot, stirring only once or twice, until the paste has darkened in color, about 4-5 minutes. This will help develop its flavor. Stir the paste into the vegetables.
Once again, use the spatula to scoot the vegetables to the outer edge of the pot. Add the spice mixture to the center of the pot and cook it only in the center of the pot, stirring constantly, until the spices are fragrant, about 30 seconds. This is called "blooming" the spices and helps develop their flavor. Stir them into the vegetable mixture.
Once again, use the spatula to scoot the vegetables to the outer edge of the pot. Add the ground turkey and use the spatula to break it up into smaller chunks as it cooks until the turkey is cooked through, about 10-12 minutes. Stir everything together until combined.
Add 1 cup of the broth and use the spatula to scrape up any brown bits on the bottom of the pot. Then add the rest of the broth, the fire-roasted tomatoes and the pumpkin. Stir until everything is combined.
Raise the heat to high and bring the chili to a boil. Lower the heat so it's at a strong simmer and let it simmer until the chili is reduced and thickened, about 10-15 minutes. Taste and add more salt or spices, if necessary. Then serve, topping each serving with avocado and bacon, if desired.