Trim the top and bottom off the leeks. Pull apart the tough green outer layers, wash them thoroughly under cold water to remove any dirt, and spread them out on an oven rack. Dry the green tops in the oven at 50°C (122°F) for several hours until completely dry and crispy.

Cut the remaining tender white/light-green leek hearts exactly in half horizontally. Use a thin knife or meat fork to make about 8 thin, shallow vertical incisions down each leek piece to ensure even cooking.

Transfer the prepared leek hearts into a metal baking tray. Top them with the lemon peel, a generous pinch of salt, a drizzle of sunflower or olive oil, and the fresh thyme branches. Cover the container tightly with aluminum foil—ensure it is fully sealed so moisture cannot escape. Bake at 160°C (320°F) for 60 to 70 minutes until perfectly tender.

Remove the foil and let the leeks cool for 5 minutes. Discard the thyme and lemon peels. Peel away and discard the thin, dry outermost layer of each leek piece. Place a leek heart onto a sheet of nori, roll it up tightly, and trim away any excess nori sheet. Repeat for all pieces.

Lay half of the nori-wrapped leeks onto a sheet of plastic wrap and zest fresh lemon over them. Place the remaining wrapped leeks right next to/on top of them, and add more lemon zest. Roll the entire bundle up tightly together in the plastic wrap to form a uniform cylinder. Knot both ends securely, rolling the log to make it extra tight. Submerge the log in an ice bath to rapidly chill, then transfer to the fridge to set overnight.

Peel and cut the onion in half. Finely chop two-thirds of the onion. Heat a drizzle of oil in a pan over medium heat, add the chopped onions and a pinch of salt, and sweat until deeply caramelized.

Cut the remaining third of the onion into wedge pieces and use a blowtorch (or a dry, screaming-hot pan/gas flame) to heavily toast and blacken the flat sides.

Once the chopped onions are caramelized, deglaze the pan with the Madeira wine. Add the toasted onion wedges, water, bay leaf, and whole coffee beans. Simmer gently on low heat for at least 3 hours. Strain the liquid through a fine sieve lined with paper towels, transfer it back to a clean pan, and reduce it over medium heat until highly concentrated and intensely flavored. Season with salt to taste.

In a small saucepan, combine the water, white wine vinegar, sugar, salt, and lemon peel/zest. Bring the mixture to a boil.

Meanwhile, trim the roots and peel the pearl onions, then slice them in half. Once the pickling liquid boils, drop the onions in and boil for exactly 1 minute. Transfer the onions and liquid into a clean jar, close the lid, let it cool completely, and store in the fridge.

Add the cashew nuts, vegetable broth, canned chickpeas, salt, and fresh lemon juice to a high-speed blender. Blend until perfectly smooth and velvety (it will look thin at first, but will firm up into a pipeable texture once chilled in the fridge).

Take the fully dried green leek tops from Step 1, place them into a clean blender, and process into a vibrant, ultra-fine green powder.

Separate the layers of the pickled sweet-and-sour pearl onions. Spread a thin layer of your green leek powder onto a small plate or tray, and press the flat, cut sides of the onion petals into the powder to coat the rims.

Using a very sharp, long knife, gently slice the chilled leek roll into 4 uniform round portions. Place one slice flat in the center of each serving plate and remove the outer plastic wrap. Generously brush the top of the cold leek round with your warm, reduced coffee broth—the warm broth will gently bring the cold leek up to an ideal room-temperature eating consistency.

Pipe small dots of the cashew nut cream onto the leek mosaic. Place the powder-rimmed onion petals on top, filling their hollows with a bit more cashew cream. Garnish beautifully with fresh edible flowers and serve immediately.