Heat the oven to 190C/170C fan/gas 5. Finely grate the zest and squeeze the juice from the lemon, then set aside, keeping them separate from each other. Put the squeezed-out lemon and the tarragon sprig in the chicken cavity. Tip the potatoes into a large roasting tin and toss with the oil and a grinding of black pepper. Sit the chicken in the middle, but not on top of the potatoes and roast for 1 1/4-1 1/2 hrs until the chicken is cooked but still moist, and the potatoes are tender and golden. Remove the tin from the oven, pour off any juices into a jug and set aside. Toss the lemon zest through the potatoes and leave the chicken to rest, covered, while you cook the greens.

Pour 150ml water into a pan and add the bouillon. Drop in the leeks, cover and cook for 2 mins, then add the asparagus and peas. Cover again and cook for 2 mins more. Finally, stir through the spinach to wilt it. Pour the roasting juices into the veg with 2 tbsp lemon juice, the yogurt and tarragon leaves, and stir well. If you're following our Healthy Diet Plan, serve half the veg with the meat from a skinless chicken leg and breast. Eat the other breast and leg with the remaining veg on another day. Will keep for up to three days, covered, in the fridge. To serve, reheat on plates in the microwave. Reserve any meat left on the carcass for our healthy quinoa salad.