For 1 swordfish steak
4 tablespoons sweetened sake (mirin)
3 tablespoons soy sauce
3 tablespoons orange juice
Juice of 2 limes
1 scallion finely diced
Mix all the ingredients for the sauce together and let the fish marinade for an hour or two (or overnight). The longer it marinates, the more tender the swordfish becomes. To speed up the marination process, you can poke a few small holes into the sides of the swordfish with a fork to let the sauce penetrate more deeply.
Remove the swordfish from the marinade, reserving the marinade for the cooking. The idea is to sear the swordfish and add the marinade in spoonfuls, cooking the fish at a high temperature so the liquid reduces and caramelizes, creating a nice glaze over the fish.
Add a little oil to a sauté pan (I used virgin coconut oil for its high temperature threshold).
When the oil begins to lightly bubble, place the swordfish steak in the pan on the highest heat and let it sear for a couple of minutes.
Add a couple of spoonfuls of the marinade and let the liquid reduce. Lower the heat slightly as the liquid begins to thicken to prevent it from burning. As it thickens, add a few more spoonfuls of marinade (it should begin to bubble a sizzle) and then let it reduce again. Repeat these steps until all the marinade has been used up and the swordfish becomes covered in a nice glaze. The process is similar to making a risotto, adding liquid and then letting it absorb. The whole process should take about 14 minutes, cooking the fish about 7 minutes a side.
This marinade can also be used to cook other big fish like cod or salmon.