Heat your oven to 200°C/Fan 180°C/Gas 6. Crumble the stock cube into a heatproof measuring jug. Add 750ml boiling water and stir to dissolve the stock cube.
Trim the top and bottom off the leeks. Finely slice them. Warm a pan over a medium heat. Add ½ tbsp. oil and the leeks. Season. Cook for 5 mins, stirring often, till the leeks have softened but don’t have too much colour. Turn the heat right down.
Tip the pearl barley into the pan. Stir to mix it with the leeks. Add a good splash of the stock. Keep adding stock and stirring every so often till the pearl barley is creamy. Continue this way for about 40 mins till all the stock has been absorbed.
While the pearl barley cooks, trim the rough ends from the fennel. Halve it and slice into wedges. Pop on a baking tray. Drizzle with 2 tsp oil and some seasoning. Rub the oil into the fennel.
Roast the fennel for 20 mins till it’s starting to brown and soften. Add the salmon fillets to the tray. Roast for another 8-10 mins till the salmon is cooked and flakes easily when you press it with a fork.
Finely chop the leaves from the dill. Stir the dill into the pearl barley risotto. Taste the risotto and add more salt or pepper if you think it needs it.
Spoon the risotto into two warm shallow bowls. Top each one with a handful of rocket. Top with the fennel wedges and salmon. Serve straight away.