1. With a sharp knife, cut the fish into thin wide slices.
2. Place in a bowl, and toss with the lime juice and grapefruit juice.
3. Let the fish sit at room temperature for approximately 15 minutes.
4. In the mean time cut the grapefruit in half at the center.
5. Using a grapefruit knife, remove sections of grapefruit.
6. Slice each section in half, the long way.
7. When ready to serve the ceviche’, drain the liquid completely from the halibut, and discard liquid.
8. Add the grapefruit pieces to the fish, along with the garlic, red chilies, green chilies and mint.
9. Toss gently.
10. Divide among 6 plates. Lay out the strips of halibut flatly on each plate.
11. Season with coarse salt, sprinkle with hot sauce, and drizzle with extra-virgin olive oil.
12. Serve immediately.