If you're lucky enough to get your hands on river trout you'll
find the flavour unsurpassable. Ocean trout or salmon can be
substituted, but you'll need to adjust the cooking time because of
the size difference.
Combine cider, 500ml water, lemon, chervil and garlic in a fish kettle or saucepan large enough to fit trout. Bring to the simmer over low-medium heat and season to taste. Gently add trout to pan and cook just below simmering point until just cooked through (6-8 minutes). Remove from liquid and serve immediately, drizzled with a little poaching liquid.