Heat oven to 400° F. On a rimmed baking sheet, toss the tomatoes and scallions with the oil; season with ½ teaspoon salt and ¼ teaspoon pepper. Roast until soft, 18 to 22 minutes.
In a large, deep skillet, add the vinegar to 3 inches of barely simmering water. In 2 batches, crack the eggs into the water and cook until the whites are set, 2 to 3 minutes.
Meanwhile, cook the grits according to the package directions. Stir in the butter. Serve the grits topped with the eggs and vegetables.
