Method

• 1.
  Place the salt and 2 cups (500ml) water in a saucepan over high heat, stirring until salt dissolves. Remove brine from heat and chill until completely cold. Place salmon in brine and set aside at room temperature for 15 minutes.
• 2.
  Remove salmon, discarding brine, and pat dry with paper towel.
• 3.
  Place oil in a flameproof roasting pan, ensuring there’s enough oil to cover salmon (add more oil if necessary).
• 4.
  Place pan over medium-low heat and bring oil to 72°C. Carefully place salmon in oil and cook, maintaining temperature at 72°C, for 10 minutes, then remove from heat.
• 5.
  Set the salmon aside at room temperature to poach in cooling oil for 1 1/2 hours or until flesh is opaque but still rare in the centre. Combine apple, fennel and fronds, eschalot, lemon juice and 2 tbs poaching oil in a bowl. In a separate bowl, combine the sour cream and the mustard. Season.
• 6.
  Divide sour cream mixture among plates and top with salmon and salad.