Melt butter in a Dutch oven over medium-high heat; add mirliton and next 4 ingredients, and sauté 5 minutes or until onion is tender.
Sprinkle with flour, and cook, stirring constantly, 2 minutes. Gradually add broth, stirring constantly.
Stir in corn and next 5 ingredients; cook, stirring occasionally, 45 minutes. Stir in lime juice. Ladle into bowls, and sprinkle each serving with cheese and bacon, if desired.
* 4 large yellow squash or zucchini, seeded and chopped, may be substituted for mirlitons.