How to Make It
Add the watercress to a serving platter, as if it were a bouquet of flowers, with the stems on one end, and leaves on the other. Slice tomatoes 1/2-inch thick and scatter them in and around the leaves, set aside.
Place the butter in a small heavy bottomed saucepan over medium heat, stirring occasionally. When the foam subsides, and the color turns to a golden brown, about 4 minutes, turn off the heat. While it's still hot, scrape out all of the melted butter and browned bits from the pan with a spatula. Pour butter onto the leaves of watercress and sliced tomatoes. Season tomatoes well with flaky sea salt and black pepper and serve immediately.