3 tablespoons vegetable oil, divided

1 1/2 pounds ground turkey

1 (1 ounce) package taco seasoning mix

1 teaspoon ground coriander

1 teaspoon dried oregano

1 teaspoon chili pepper flakes

2 tablespoons tomato paste

1 (14.5 ounce) can beef broth

1 (7 ounce) can salsa

1 (14.5 ounce) can crushed tomatoes, or coarsely chopped tomatoes packed in puree

1 (7 ounce) can chopped green chile peppers

1 medium onion, finely chopped

1 green bell pepper, diced

3 medium zucchini, halved lengthwise and sliced

1 bunch green onions, chopped

1 cup sour cream

1 cup shredded Cheddar cheese