While I love slow-roasted salmon served at medium rare, I recommend cooking the salmon to medium, which is an internal temperature of 130-135 degrees. I tried the salmon in this recipe at both medium rare and medium and found the texture worked better for tacos at medium. Note that the USDA recommends cooking salmon to 145 degrees, but that will leave you with dry, unsatisfying salmon. No one wants that. Plenty of world-renowned chefs cook their salmon between medium rare and medium.