Smoked Bonito, Salted Grilled Plums and Onion

• 20 sweet onions, peeled,
• 2 litres (70 fl oz/8 cups)

Heat a large chargrill or barbecue on medium–high heat. Add the onions and grill until charred, about 5 minutes. Set one onion aside for later use. Combine the chicken stock with the remaining charred onions in a bowl and steam over a double boiler for 4 hours. Pass the mixture through a fine sieve and put it in a clean saucepan over medium heat. Reduce the liquid by two-thirds.

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