Preheat the oven to broil.
Put the butter in a cast-iron skillet or ovenproof frying pan over medium-high heat. Stir and swirl the pan occasionally, for about 3 minutes. Let the butter foam and settle – it will change to a golden brown color and smell nutty.
Add the maple syrup and let it dissolve into the butter.
Add the garlic and ginger and sauté for one minute, until fragrant.
Add the fresh lemon juice and stir well to combine.
Add the salmon steaks to the pan, skin side down. Cook for 3 to 4 minutes, the sauce will turn golden and bubbly. Use a spoon to baste the tops with juice from the pan as they cook.
Season with thyme, cayenne, and salt.
Surround the fillets with lemon wedges.
Transfer the pan to the middle rack of the oven and bake for another 3 to 4 minutes, or until the salmon taps are barely charred.
Remove from heat and use a spoon to baste the tops again.
Garnish with optional thyme and serve over a bed of dark leafy greens with a side of steamed asparagus, broccoli, or Brussels sprouts.