Poblano Chiles Stuffed with Cheese

This is one of the most traditional, and most loved, dishes of Mexico.

3 tablespoons olive oil
1 onion, minced
2 carrots, peeled and thinly sliced
10 tomatoes, roasted, peeled, seeded and chopped
1/2 cup white or cider vinegar
3 tablespoons granulated sugar
2 tablespoons oregano
16 poblano chiles, toasted, skinned and deveined
14 ounce queso fresco (farmer