Segment the grapefruit over a large glass bowl. Allow the juice to remain in the bowl.
Segment the grapefruit over a large glass bowl. Allow the juice to remain in the bowl.
Remove some of the skin from the cucumber, slice in half, length wise, and remove the seeds. Cube, and add to the bowl. Thinly slice the red onion. Quarter the tomatoes, remove the seeds, and cube.
Add to the bowl. Pit the Kalamata Olives and add to the bowl along with the cilantro. Squeeze lime juice and add sesame oil over the mixture and season with salt and pepper.
Stir in sesame seeds and refrigerate for one hour or longer.
In a hot skillet, add a small amount of olive oil.
Season the tuna with salt and pepper, and place in the hot skillet.
Sear each side until golden brown, about 1-2 minutes per side.
The center of the tuna will remain pink. Allow to rest for about 5 minutes before slicing thinly.