Peel and crush the roasted Anaheim chiles; set aside.
Remove the fat from the pork shoulder and cut the fat into small pieces. In a large pan over medium-high heat, fry the fat until crisp, 4 or 5 minutes, and then remove the chunks of fat from the pan.
Sweat the onions and garlic in the same saute pan, cooking them in the residual pork fat. Cut the pork shoulder into 1/4-inch pieces and add them to the pan and saute until browned. Add the bay leaves, oregano, tomatoes, and Anaheim chiles. Simmer over low heat for about 25 minutes. Add the water, chicken base, and salt, to taste. Bring to a boil and then cover and simmer for 2 hours or until tender.
Slowly add the flour in small amounts, until the mixture has reached your desired thickness; do not exceed 1/4 cup flour. If desired, return the crispy fat to the mixture to add additional pork flavor. Serve in bowls and garnish with fresh cilantro leaves.
