Cut each ball of cheese in half crosswise and place the halves, cut side down, on 4 salad plates. Cut each tomato in half through the stem end and distribute them around the burrata. Drizzle the tomatoes and burrata generously with olive oil and balsamic vinegar and sprinkle with kosher salt and pepper. Scatter the basil on the salads, sprinkle with fleur de sel, and serve with Garlic Toasts.
Preheat the oven to 400 degrees F.
Slice the baguette diagonally into 1/4-inch-thick slices. Depending on the size of the baguette, you should get 20 to 25 slices.
Lay the slices in one layer on a baking sheet, brush each with olive oil, and sprinkle generously with salt and pepper. Bake the toasts for 15 to 20 minutes, until they are browned and crisp. As soon as they are cool enough to handle, rub one side of the toasts with the cut side of the garlic. Serve at room temperature.