Place poblano peppers on a baking sheet under the broiler. Roast until the top side has a nice char, then rotate and roast the other sides. Remove from oven and let cool to a temperature you can comfortably touch.
Preheat dutch oven to medium-high heat. (If you’re using a slow cooker instead, preheat a large skillet.)
Brown the meat. Add onions, garlic, jalapeno, and red peppers. Continue cooking, stirring frequently, until the onions begin to soften.
If you’re continuing with a slow cooker instead of the dutch oven on the stovetop, carefully transfer the ingredients from the skillet to the slow cooker. If using the dutch oven, continue with the ingredients in the dutch oven.
Add the remaining ingredients and stir to combine. If using the dutch oven, bring to a boil, reduce to low, and cover. Cook for at least 2 hours, stirring occasionally (I think I cooked it for about 4 hours). For the slow cooker, get it started on high for about an hour, then reduce to low for at least a couple of more hours.
Serve topped with cheddar cheese and sour cream if desired.