Remove the salmon from the fridge and let it rest for 10 to 20 minutes.
In a small bowl, mix together the garlic powder, salt and pepper.
Place the salmon filet, skin-side down, on a plate or cutting board. Sprinkle the seasoning mixture evenly over the salmon and gently rub it in.
Preheat a cast iron skillet over medium-high heat with the olive oil, until the oil in shimmering. The bottom of the pan should be coated in oil. If not, add a little more oil.
Place the salmon, skin side down, into the pan and sear for 4 minutes until the skin becomes slightly crispy and golden brown.
Carefully flip the salmon using two spatulas, sear for 2 more minutes then gently flip it back over. Add the butter to the skillet and let it melt.
Reduce the heat to medium heat and spoon the melted butter over the salmon as it cooks for an additional 2 minutes.
Garnish with freshly sliced lemons and dill, if desired.
Notes
Storage: Store leftovers in an airtight container in the fridge for up to 2 days.