Place a large heavy-bottomed stock pot over medium heat. Add the olive oil, and once it is warm, add the diced onions and peppers and cook, stirring, until the onions are transluscent, about 3 minutes.
Add the ground turkey and using a spatula, break it apart into pieces and cook it until it is cooked through.
Add all of the remaining ingredients, except for the optional toppings, then reduce the heat to low and simmer the stew until it is heated throughout.
When ready to serve, crumble a handful of tortilla chips into a bowl then ladle in the stew and top it with sour cream, shredded cheese and sliced scallions (optional).