Heat oil in large frying pan. When hot, add onion and garlic and saute until translucent and soft (8-10 mins).
Next add chopped Roma tomatoes and oregano and cook for about 5 minutes.
Then add your shredded chicken, chipotle chiles and chicken broth. Cook on medium-low for about 30 minutes until most liquid is absorbed and the flavors blend.
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Chicken Tinga (Tinga de Pollo) recipe