Cut the chicken breasts into 2 in (50 mm) strips. Peel and chop the onion finely. Heat 2 tablespoons of the olive oil in a frying pan, then add the vinegar and onion, and cook for 3 minutes over a medium heat.

Add the chicken and cook for a further 3 minutes, stirring occasionally. Add the vermouth or wine, and the lemon juice, and reduce the heat so that the sauce is just simmering.

Meanwhile, drain the tin of artichokes and cut them into bite-size pieces. Trim the mangetout and break up the broccoli into tiny florets.

Roughly chop the tarragon leaves, discarding the stalks, and add them to the chicken in the frying pan, along with the sugar and artichokes. Stir in the yoghurt, adjust the seasoning and continue to simmer over a low heat.

Add the pasta and remaining oil to a large pan of boiling salted water, and cook according to the instructions on the packet. Add the mangetout and broccoli florets to a smaller pan of boiling salted water and cook for 2 - 3 minutes.

Drain the pasta and vegetables as soon as they are cooked. Spoon the chicken, artichokes and sauce over the pasta, and arrange the green vegetables around the plate. Serve immediately.