Put a sieve or fine mesh strainer over a sauce pan. Pour the grapefruit juice into the strainer, separating the seeds and pulp from the juice. Discard the pulp and leave the juice in the sauce pan.
Place the sauce pan onto a stove top and turn the heat on medium high. Add the garlic, ginger and grapefruit zest. Allow the grapefruit juice mixture to come to a boil, then add the tamari (or the substitute of your choice) and apple cider vinegar. Let the mixture come to a boil for 2-3 minutes, until reduced by 1/4. Then, reduce it to a simmer.
As the glaze is simmering, dry the salmon fillets on all sides with a paper towel. Season all sides (skin included) generously with salt. Then, sprinkle turmeric powder on all sides (skin also included!) Don't be shy here with the seasoning!
Heat a large skillet over high heat. Season the skillet with 1 tbsp of coconut oil. Allow the oil to come to a shimmer (should be piping hot!) then place the salmon fillets skin side down onto the pan. Sear for 3-4 minutes, until the skin is golden brown and crisp. Flip the salmon onto the other side and let it sear for another 2-3 minutes, until golden brown. Then, tilt your pan and allow the oil to well up around the edges. Sear the sides of the salmon in the oil for 30 seconds-1 minute. Once all sides are seared, adjust the heat to medium and flip the salmon so the skin side is down against the heat.
Check on the glaze. It should be reduced by about 2/3 by now, and have a glossy, glazey consistency. If this is the case, remove the pan from the heat. Put a seive or fine mesh strainer over a bowl and pour the glaze through the strainer to separate the smooth glaze from the aromatics. Discard of any pulp or strained out aromatics.
Raise the heat on your salmon pan to medium high. Pour half of the glaze onto the salmon fillets so that the top of each is fully coated (each fillet should get about a quarter of the glaze.) Use a pastry brush or rubber spatula to fully coat the sides of the fillets in the rest of the glaze. Flip and coat the bottom as well. The glaze will begin to bubble on the bottom fo the pan. Feel free to grab a spoon and pour the bubbling glaze over the salmon as it continues to reduce in the skillet. You don't want any of it to go to waste!
Plate the salmon with some chopped scallions and cilantro, plus a side of your choice (I prefer something fresh and crunchy like my cabbage salad with a lime and avocado oil dressing and cara cara oranges, but that's just me!) Enjoy immediately!