In a blender or food processor, combine the tomatoes, onion, garlic, jalapeño to taste, and 1 cup (8 fl oz/250 ml) of the stock and process until smooth. Pour into a slow cooker.
Add the chicken thighs, the remaining 4½ cups (36 fl oz/1.1 l) stock, the juice of 1 lime, the vinegar, cumin, bay leaves, 4 teaspoon salt, and several grinds of pepper. Cover and cook on the low setting for 5 hours. The chicken should be very tender.
Transfer the chicken pieces to a plate. Remove the meat from the bones, and discard the bones. Chop or shred the meat. Using a large spoon, skim away the fat from the braising liquid. Return the chicken meat to the slow cooker. Add the corn kernels, cover, and cook on the low setting until tender, about 30 minutes more. Remove and discard the bay leaves.
Cut the remaining 2 limes into wedges. Ladle the soup into warm shallow bowls, distributing all the ingredients evenly. Garnish each bowl with some of the avocados, cilantro, and tortilla chips. Serve at once. Pass the lime wedges at the table.
Serve this zesty soup with a tossed green salad for an easy weeknight supper. The creamy avocado, sweet corn, and cilantro add a splash of color and fresh flavor and the tortilla chips deliver a pleasant salty crunch to the soup. If fresh summer corn is out of season, use thawed frozen corn kernels and reduce the cooking time to 15 minutes.
Note: I did this with chicken breasts instead of thighs and added a can of pinto beans and it turned out great!
