Coat the swordfish with the salt and pepper and place in a vacuum seal bag.
Cook for 45 minutes.
Remove and pat dry.
Heat the butter in a skillet over medium heat and add the shallots and thyme.
Cook for 3-5 minutes, until shallots have softened.
Add the grapefruit juice and simmer 2-3 minutes.
Serve the swordfish topped with the grapefruit and shallot sauce. Garnish with chunks of fresh grapefruit if desired.
Notes
To ensure the swordfish pieces cook evenly, buy steaks that have the same thickness (around 1 - 1½ inches thick).
If your steaks are really thick, you may need to increase the cooking time by about 15 minutes or so.
When sealing the bag, make sure the steaks are in a single layer. This will help them cook evenly.
Make sure the air is removed from the sealable bag to avoid bacteria getting into it.
The bag of swordfish should be completely submerged in the water bath. You can always use something heavy like a sous vide sinker weight to ensure it doesn’t float.
If you don’t weigh it down and it starts to float, just open the bag, remove the air and reseal it.
The swordfish skin is tough. I usually keep it on while cooking but I don't eat it. You can remove it before cooking, but it’s easier to remove it once the fish is cooked.
Swordfish steaks will have a red bloodline going through them. These red areas have a strong flavor but they indicate freshness. If these areas are brown instead of red, it means the swordfish is old.