Tarragon Chicken

Tarragon chicken has a reputation for being a bit of a 'Delia Dish'- you know, those complicated, boiled for hours, overtly traditional French classics. Delicious, but you feel so battered with the various steps and formality of it, you feel completely averse to serve it for a relaxed dinner.
As a result, in just such a third-world emergency, I come to save the day. This is a frank, fast, and fresh version, that is one of my regulars.
Tarragon is a highly underused herb, and as much as I would love to be the contrarian and call it highly underrated, it is quite exclusive. It has a specific, strong, dill/tea flavour that doesn't go with many things. Fortunately, the French utilise it perfectly here, with that heady herbal flavour working perfectly in the rich vermouth sauce. Simon Hopkinson names it 'chicken's favourite herb', as a matter of fact.
There's a time and a place for chicken thighs, but it's definitely not here; best-quality white meat, please.
1)This is how to make some sides which go really nicely here, but feel free to have whatever veg and starch you want here. Something fresh and green works best. Steam a bag of iron rich leaves, spinach, baby chard, rocket all great, and steam them over some boiling new potatoes, for just a minute or so, until they wilt a bit, then squeeze them dry and spread on a plate to cool. It may be odd to do them a good 20 minutes before you serve, but a lesser-known secret is that spinach at room temperature, is fabulous.
2)Finely chop one white onion, and crush 3 cloves of garlic, and saute them in some butter, and let them really sweat, then add about 1 tbsp of dried tarragon and cook them until really soft, then add your chicken breasts to the pan, and cook them on both sides for about 2 minutes.
3)Add about 1 glass of vermouth (or dry white wine, I always keep vermouth in the house to do white wine's job) and the same amount of water, and poach the chicken until it's done.
4)Remove the chicken from the sauce, and wrap it tightly in foil to keep it juicy and hot, whilst you add a little chicken stock concentrate to that sauce, plus some more butter, freshly chopped tarragon and let it reduce well. Sometimes I add a little cream or cornflour and make a creamy sauce, but not today. Add a spritz of lemon juice, too. Keep tasting the sauce to see when the alcohol cooks off, and if it needs any salt, and white pepper.
5)Smash your new potatoes, I don't mean mashing, just break them and add a little butter and some chopped tarragon, and dress the leaves with some extra virgin olive oil.
6)Return the chicken to the sauce, and sprinkle over some more fresh tarragon.