Chiles Poblanos Rellenos de Queso (Poblano Chiles Stuffed with Cheese)

In a large saucepan, cover the tomatoes with water and cook until they change color and their skins begin to peel. Remove the tomatoes from the water and let cool, reserving the cooking liquid. Once cool enough to handle, peel the tomatoes. Transfer to a blender or food processor, add the onion and garlic, and blend until smooth. In a large skillet, heat the oil until hot but not smoking. Add the tomato sauce and fry, stirring occasionally, until it changes color and is fully cooked. Add the bay leaf and enough of the reserved tomato cooking liquid to make a fairly thin sauce, then season to taste with salt. Keep hot until ready to serve.