Remove the stem from the tomato. Flip it over and cut a cross in the bottom. Remove the flesh from the grapefruit. Thinly slice the cheese.
Place the tomato into the center of a heat-proof dish. Stuff the cheese into the slits of the tomato. Place the grapefruit sections around the edges of the tomato and scatter the nuts over the top.
Drizzle the oil over it and sprinkle with salt. The amount of salt and oil is up to you. Just a little bit of salt will bring out the taste and make it delicious.
Bake for about 20 minutes at 180°C until a toothpick can slide through the tomato very easily.
Use a spoon to cut the tomato, combine with the now sauce-like grapefruit, and enjoy. It's so delicious that you'll find yourself drinking the excess sauce.