Arrange all ingredients for use.
Halve the lemon and place in a large pan.
Add 400ml water and the pepper and coriander seeds. Bring to the boil, then reduce the heat. Wash the salmon, place it in the pan and poach for 10-15 minutes over a low heat.
Wash and halve the tomatoes.
Wash the coriander, shake dry and chop.
Wash the chillies and cut into thin rings.
Peel the avocado, halve and remove the stone.
Dice the flesh.
Mix the avocado pieces, tomatoes, chilli and coriander in a bowl and season with lime juice, salt and pepper.
For the rösti, peel and finely grate the potatoes.
Wrap in a tea towel and squeeze out the excess liquid.
Tip the potatoes into a bowl and season with salt, pepper and nutmeg.
Place 4 heaps of the mixture into a large non-stick pan with hot oil and flatten with a spatula. Cook gently for for 3-4 minutes until golden brown, then turn and cook for another 3-4 minutes.
Arrange the rösti on plates, spoon on the salsa and top with the drained salmon. Season lightly with salt and pepper, and serve.