500 gm kipfler potatoes, scrubbed
50 ml white wine vinegar
1 egg, at room temperature
1 cup watercress sprigs (loosely packed)
½ cup flat-leaf parsley, torn (loosely packed)
100 ml olive oil
1 smoked fish, coarsely flaked (skin and bones discarded)
3 dill pickles, sliced
Whole-egg mayonnaise, to serve

Place potatoes in a large saucepan, cover generously with cold salted water, bring to the boil over medium-high heat, reduce heat to medium and gently boil until tender but holding their shape (30-35 minutes).
Drain, then, when cool enough to handle, peel and slice into thick rounds.
Combine in a bowl with vinegar, season to taste and stir to coat.
Refrigerate for flavours to develop (at least an hour, or overnight).

Cook egg in a saucepan of boiling water (8 minutes for hard-boiled), drain, refresh under cold running water, peel and set aside.

Add watercress, parsley and oil to potatoes and mix well with your hands until leaves are coated and glossy.
Layer the potato mixture, trout and dill pickles on a platter.
Finely grate egg over, dollop with mayonnaise to taste and serve.