Take butter out of the refrigerator and let it sit on the counter for about 30 minutes to soften.
Add butter to a mixing bowl and add pressed garlic and herbs. You can either use a blender or simply mix it with a fork. Mix it until all ingredients are incorporated throughout the butter.
Prepare the coals for the grill until ashed over and make sure to clean the grill grate. Set the coals to the lowest level away from the grill grate.
Pat salmon fillets dry with a paper towel.
Season each fillet with salt on all sides. Use most of the butter to coat each piece and set some aside to top off salmon after it is cooked.
Place each salmon fillet on the grill skin side up first. Close the lid and cook salmon for 3-4 minutes before flipping. Salmon will release once it’s cooked enough so don’t try to mess with it or move it too soon.
Flip each fillet using a fish spatula, close the grill, and let it cook for another 4-6 minutes. A 1 1/2 – 2 inch salmon fillet will take 8-10 minutes to cook.
You can also use a meat thermometer to measure the internal temperature of the thickest part of the fish. Salmon is done when reaches 145°. Take it off the grill when it is about 142° and let it rest to get to temp all the way.
Top each piece of salmon with a teaspoon or so of herb butter while still hot.