Heat your oven to 200C/Fan 180C/Gas 6. Add 1 tbsp olive oil to a small roasting tin and place in the oven to warm. Trim the very tops and bottoms off your leeks. Slice a cross into the top third of the leek and rinse out any grit. Slice them in half horizontally so you have 6 round leeks.
Lay the leeks in the warm roasting tin and season with salt and pepper. Turn to coat in the oil and seasoning. Roast for 30 mins till tender. When cooked, take out of the oven and cover the tin with foil to keep the leeks warm.
Place the tomatoes in a bowl and cover with boiling water. Leave to soak for 15 mins. If you have a gas hob, turn on the smallest burner and lay the pepper directly on the flame, Char, turning the pepper, for 15 mins, till black all over. Alternatively, halve, dressed and grill skin side up or fry in a dry frying pan, skin side down, till black.
Pop the pepper in a bowl. Cover with cling film and leave for 10 mins too cool, then pull off the black skin (it’s OK if you can get all the skin off).
While the pepper cools, rinse the barley and tip into a pan. Cover with boiling water. Add a pinch of salt. Pop on a lid. Bring to the boil, then turn down the heat and simmer for 20-25 mins till tender.
Warm a dry frying pan. Add the flaked almonds. Toast for 2-3 mins, shaking the pan occasionally, till golden. Tip into a food processor. Add the skinned, deseeded pepper. Drain the tomatoes and add them. Peel and roughly chop the garlic and add that. Roughly chop the parsley stalks and add them (keep the leaves for later).
Add the vinegar, smoked paprika and a pinch of chilli powder with 1 tbsp olive oil. Blitz to make a chunky sauce. Taste and adjust the seasoning.
Drain the barley. Roughly chop the parsley leaves and toss most with the barley. Heap on two warm plates with the roast leeks. Spoon over the warm romesco sauce. Garnish with the last of the parsley leaves.