In a 12" heavy skillet saute garlic in oil over moderately high heat,
stirring just until fragrant. Add scallions, zucchini, pattypan
squash, corn, salt, and pepper to taste and saute, stirring
occasionally, until zucchini and squash are golden in spots, about
4 minutes.
Add broth and simmer ragout, covered, 3 minutes, or until squash is
just tender. Add tomatoes and tarragon and simmer, covered, 1 minute,
or until tomatoes are softened.
Season ragout with salt and pepper and serve warm or at room
temperature.