Preheat the oven to 220°C/200°C fan and line a roasting tin with baking paper.
Put the pearl barley into a saucepan with half a teaspoon of salt and plenty of water. Bring to a gentle boil, cover and cook for 30 minutes until tender. Drain and set aside.
While the barley cooks, in a bowl, stir together the marinade ingredients.
Put the cabbage, pak choi, spring onions and green beans in the lined roasting tin and add a generous pinch of salt. Toss with the olive oil and 2 tablespoons of the marinade until coated. Roast for 15 minutes.
Meanwhile, in a large bowl, coat the salmon fillets in the remaining marinade.
After 15 minutes, lay the salmon fillets on top of the vegetables in the roasting tin and spoon over any leftover marinade. Return to the oven for 15 minutes until the salmon is cooked through.
In a bowl, mix the cucumber salad ingredients together.
Stir the pearl barley through the roasted vegetables so it's coated in the gochujang juices. Garnish the salmon with the chopped coriander and enjoy with the cucumber salad on the side.
