* Preferably 1 of yellow cornmeal and 1 of blue. ** or mozzarella cheese or a combination of both Cut the tortillas into 1 cm wide strips and leasve them uncovered at room temperature until they are dry and crips, about 24 hours (or heat in iron skillet until dry and hot).
In a 4 litre saucepan over low heat, melt the butter. Add the onions, garlic, oregano, and bay leaves and cook, covered, stirring once or twice, for 10 minutes. Stir in the chicken broth, potatoes, salt, cumin & black pepper and bring to a boil. Lower heat and simmer, partially covered, stirring once or twice, until the potatoes are very tender, about 25 minutes.
Stir in the cream and adjust the seasoning if necessary. The soup can be prepared up to 3 days ahead. Cool it completely and refrigerate, covered. Rewarm it over low heat, stirring often, until steaming.
Ladle the soup into wide bowls, sprinkle the cheese over the soup, and scatter the tortilla strips over the cheese. Serve immediately.
Serves 4 to 6.