Trim and gently scrub 250g of young, slim carrots. Slice them in half lengthways and put them in a roasting tin. Preheat the oven to 180C/gas mark 4. Halve 150g of small aubergines and add them to the carrots. Wipe and trim 250g of courgettes, then cut them in halves or quarters lengthways, depending on their size, then add them to the roasting tin.
Trim and scrub 2 or 3 small beetroot. Cut them into quarters, then mix them with the other vegetables. Add 6 whole, unskinned cloves of garlic to the tin. Pull the needles from a couple of stems of bushy rosemary, chop finely and scatter over the vegetables, pour over 4 tbsp of olive oil, season with salt and black pepper, then toss everything together so the vegetables are glossily coated in oil and seasoning.
Roast in the preheated oven for about 45 minutes, occasionally turning them over in the tin.
While the vegetables roast, make the dressing. In a blender or food processor, mix together 2 lightly heaped tbsp of mayonnaise, 100g of soured cream and 3 lightly heaped tbsp of yoghurt. Season with 1 tbsp of dijon mustard, 2 tbsp of white wine vinegar, as you wish, and a little black pepper. Crumble in 150g of blue cheese and process until smooth and creamy. Transfer to a small bowl.
Remove the roast vegetables from the oven and divide between 2 plates, then trickle over the blue cheese sauce. Serves 2. Ready in 1 hour.
When I say blue cheese I suggest something quite tart and punchy, such as stichelton, stilton or one of the British blues rather than a softer, more gentle variety such as gorgonzola (Danish blue is a worthwhile cheap option).
Save a little extra cheese to crumble over the sauce as you serve it.
Taste the sauce as you go along, adding more mustard, cheese or vinegar, as you wish. There may be some left over. Use it to dress crisp lettuce or as an accompaniment for cold roast chicken or as a dip for raw vegetables.
Follow Nigel on Instagram @NigelSlater