Giorgio Locatelli's green bean salad with roast red onion and Parmesan (Insalata di fagiolini, cipolle rosse e parmigiano)

Serves 4

• 2 large red onions
• 300g red wine vinegar
• 1 tbsp sugar
• 100g extra virgin olive oil
• 0 freshly ground black pepper
• 240g fine green beans
• 2 tbsp freshly grated Parmesan cheese
• 3 tbsp shallot vinaigrette
• 1 bunch chives

Step 1
Preheat the oven to 220C/gas mark 7.

Step 2
Leaving their skins on, wrap the onions in foil and bake in the oven for about 1 hour until soft.

Step 3
While the onions are cooking, put the vinegar into a small pan and boil until reduced by about a third.

Step 4
Remove from the heat, stir in the sugar until dissolved, then stir in the extra virgin olive oil to make a vinaigrette.

Step 5
When the onions are cooked, unwrap them and peel off the skin.

Step 6
While they are still warm, cut them in half, separate the layers and season with salt and pepper, then put them into the vinaigrette.

Step 7
Blanch the green beans in plenty of boiling salted water for about 5 minutes, then drain.

Step 8
Place in a bowl, sprinkle with the grated Parmesan and season with salt and pepper.

Step 9
Toss with the shallot vinaigrette (see recipe below) and sprinkle over the chives.

Step 10
Arrange the onion layers on your serving plates.

Step 11
Place the beans on top and shave over some more Parmesan.