In a 4- to 5-quart pan, mix masa flour with 1 cup broth until smooth.

Stir over high heat until the mixture boils.

Reduce heat to medium-low and stir until masa is thick, about 2 to 3 minutes.

Pour onto a flat plate and spread evenly to make a 3/4-inch-thick cake.

Let cool.

Rinse the pan and add the remaining broth and garlic.

Cover and bring to a boil over high heat.

Trim and discard zucchini ends.

Cut zucchini into 3/4-inch cubes.

Add zucchini to the pan, cover, and simmer for 5 minutes.

Discard husks and silks from corn.

Cut corn crosswise into 1-inch-thick wheels.

Cut masa into 3/4-inch chunks.

Add corn and masa chunks to broth.

Cover pan and return to boiling over high heat.

Simmer until corn is hot, about 3 minutes.

Ladle into bowls and sprinkle with cilantro.

Serve with lime wedges, salt, and pepper to season portions to taste.