Adjust rack to center of oven. Preheat oven to 400 F. Shuck the corn, coat theears lightly with oil and spread on a sheet pan. Place the pan in the preheated oven and let corn roast for 20 minutes. Remove the pan from the oven and let the corn stand until the ears are cool enough to handle. Working over a large bowl, carefully scrape the kernels from the cob into the bowl. Discard the cobs. Add the chopped shallots, garlic, scallions, peppers and tarragon to the corn. Mix in the oil and vinegar. Season with salt and pepper to taste. Mound the corn salad in the center of a large plate. Arrange the sliced tomatoes around the edge. Serve at room temperature.

Note: The relish can be made the day before, covered and refrigerated.