Wash the vegetables. Roast the poblano peppers and place them in a plastic bag to steam so you can peel off the skins. Boil the tomatoes just until they are soft, not fully cooked, along with the serrano pepper. Blend the tomatoes, onion, a clove of garlic, and the chicken bouillon cube. In a small pot, sauté a piece of onion, then add the blended sauce and cilantro. Simmer over low heat.

Peel the poblanos, then stuff them with cheese. Dredge the stuffed peppers in flour. Separate the egg whites and yolks, and beat the whites with a pinch of salt until stiff, then fold in the yolks. Dip each stuffed pepper in the egg mixture. Heat oil in a skillet, and when hot, fry the peppers, turning to brown all sides. Remove and drain excess oil, then add them to the sauce.

Let the peppers simmer in the prepared sauce. Taste for salt and let cook for 10 to 15 minutes. Serve hot.