In a medium bowl add the onion, garlic, lime juice, Jerk Seasoning, salt, and pineapple juice. Stir to combine. Place the salmon into the marinade and marinate for 1 hour in the fridge. 

Heat the oil in a 12-inch nonstick skillet over medium high heat. Once the oil is hot and  shimmering, place the salmon in the pan skin side up. Cook the salmon for 2-4 minutes. 

 If you want to create a good sear and crust on the salmon, do your best to resist tampering with it while it cooks.

Carefully flip the filets and add the remaining marinade. Bring the sauce to a simmer for about 2 minutes. Remove the salmon from the pan and take the sauce off of the heat, stir in the cilantro and the butter. 

Pour the sauce onto the salmon and serve over rice, beans, or greens.