Pour the stock into a small saucepan, bring it to the boil and keep it just below the boiling point.
Finely chop the shallots, garlic and celeriac. Cut the parsley roots into small cubes measuring 1⁄2 x 1⁄2 cm.
Heat the oil and butter in a heavy-based pan and sauté the parsley roots, shallots, garlic and celery for approx. 5 minutes, until tender but not browned.
Turn up the heat, add the pearl barley and sauté well for approx. 1–2 minutes.
Pour in the white wine, stir well and season with salt and pepper. Turn down the heat and add the hot stock a little at a time, stirring continuously. Allow the pearl barley to absorb most of the stock before adding more. Continue to add vegetable stock for approx. 25–30 minutes, until the pearl barley is tender but not overcooked.
The barley risotto should have a very smooth and creamy consistency.
Finely chop the shallot, dice the apple and parsley root into small cubes of 1⁄2 x 1⁄2 cm and keep them separate.
Put the butter in a saucepan and heat it until it starts to sizzle. Turn down the heat and let the butter sizzle until it is light brown and smells of hazelnuts.
Add the diced parsley root, let them fry briefly in the butter until they take on some colour, then add the shallots, apples, capers, thyme and lemon juice. Heat through briefly.
Divide the lasagne between warm plates, spoon the browned butter and filling over the top, and serve immediately.
