Drizzle the tomato slices with olive oil then season with salt and pepper. Let sit for about 10 minutes.
Heat a large griddle or grill over medium-high heat. Add the slices of bread and cook until grill marks appear, about 1 minute. Flip and cook for an additional minute.
Top each slice with burrata followed by tomato slices, avocado and watercress. Slice each toast in half.