Preheat the oven to 180°C/350°F/gas 4. First make the marinade for the vegetables. Measure the oil into a teacup, jug or other small receptacle. Finely grate the lemon zest into the oil. Peel and crush the garlic, and peel and grate the ginger, then add them too. Finely chop the herbs into the mixture. Squeeze the lemon juice in – as much of it as you can squish out – stir together and set aside. Peel the onion, chop into quarters and place in a roasting dish. Wash then chop the carrots into thick rounds and add to the roasting dish. Peel and dice the potato and put it in too. Pour the marinade over the top and shake to coat the vegetables. Pop the roasting dish into the preheated oven for an hour or so, shaking occasionally to loosen the vegetables and re-coat them in the marinade. When the carrots and potatoes are tender, remove the vegetables from the oven and tip into a food processor. Dissolve the ½ stock cube in 500ml of boiling water and pour this stock into the food processor (to cover the vegetables). Blend until smooth, and serve with a flourish of parsley and a smile. Tips: Add a swirl of natural yoghurt and/or honey at the end, to make this soup extra special. Since it’s quite a lot of effort for a soup, make double the amount and freeze half of it to have an indulgent treat on tap. You can replace the fresh carrots with a small tin of carrots – simply drain and rinse them, and add in place of the chopped carrots. The same rule applies to tinned potatoes, but as these tend to be small, use four or five, and halve the roasting time, since they will cook more quickly than their fresh counterparts.