Preparation

• In a small, heavy saucepan, bring the coffee, vinegar, and maple syrup to a boil. Lower the heat, and simmer
  until the mixture turns syrupy, 10 to 12 minutes. Remove from the heat and stir in the lemon juice and cardamom. Whisk in the butter, cover, and keep warm.
• Heat the oil in a large nonstick skillet over medium-high heat until hot but not smoking. Season the salmon with salt, and add to the skillet skin side down. Cook, undisturbed, until deeply golden, 3 to 4 minutes. Turn and cook until just barely cooked through, 2 to 4 minutes more.
• Divide the salmon among serving plates, and drizzle with the sauce.