Season the salmon fillets with salt and freshly ground pepper
Heat the oil in a large skillet over medium-high heat, sear the salmon fillets skin side up until golden brown (about 5 mins), and then flip and cook skin side down until the skin is crispy and golden (another 5 mins)
Remove the salmon fillets from the skillet and transfer them to a plate. Reduce the heat to medium-low and add the butter. Saute the garlic in the melted butter for about 30 seconds
Mix in the flour and cook for about a minute
Whisk in the cream and cook until thickened. Add the lemon zest, lemon juice, and chopped dill. Mix well and season with salt and freshly ground pepper
Return salmon fillets to skillet and cook with the sauce for about 2 minutes. Serve with crushed red pepper flakes on top.