1.Preheat oven to 200°C. Cook potatoes in a saucepan of boiling water, salted well.
2.Transfer potatoes to a baking dish with 2 tablespoons oil, thyme and salt. Toss to coat.
3.Bake 35-40 minutes, turning halfway, until golden brown. Generously sprinkle salmon skin with remaining salt and set aside 5 minutes.
4.Heat remaining oil in large frying pan on high. Cook salmon, skin-side down, 3-4 minutes until flesh is opaque but still pink in centre. Turn and cook 2-3 minutes.
5.In a small bowl, whisk mayonnaise, juice and half chives together. Season to taste.