Dice perfect ½-inch (0.7-mm) squares of fennel, and cook half in salted water until they are tender. Drain and cool on a plate.
Keep the rest raw. With the scraps of fennel you will inevitably generate turning a multilayered root into cubes, make the fennel stock and the burnt fennel oil.
For the burnt fennel oil, roast the fennel scraps at 400°F (200°C) until half-burned. Dehydrate at 140°F (60°C) and then blend with pure olive oil to make a smooth, black oil. Burnt fennel oil sounds like it would be bitter, but it’s not.
For the stock, simmer the scraps and water until the flavor is sweet and concentrated. To make the fluid gel, strain the stock, measure the appropriate amount and boil it with the agar and the reserved cooked fennel. Cool until solid, and then blend until smooth. Season with dried fennel pollen, champagne vinegar and salt.
We get the fromage blanc undrained—that is, sitting in its whey—and then we drain what we need every day. Drain it enough to make a thick purée, and season with salt. Transfer to a siphon, and charge twice.
Combine all of the ingredients for the buckwheat crisp—it's similar to the rye crisp on page 132. Transfer to a fine strainer and shake over a Silpat in an even layer. Bake in the Combi at 340°F (170°C) and medium fan for about 8 minutes, rotating at 4 minutes, until lightly browned. Turn the Silpat onto a piece of parchment set on the counter, and peel back the Silpat. Break into pieces and store in a tightly covered container.
Blend the wheatgrass juice with the pure olive oil and xanthan to make a nice sauce. The wheatgrass juice should be very fresh, juiced within a few hours. If you want to juice it yourself, I encourage that, but it needs a special juicer. An expensive one, of course.
To serve, toss the raw and cooked fennel in some of the fennel gel, just to coat and season. Taste and add champagne vinegar or salt if necessary. Place 6 each raw and cooked pieces in the center of the plate, with a little of the fluid gel. Place a drop of the burnt fennel oil on each corner (shake the bottle first). Drizzle the wheatgrass juice around it, dispense some fromage blanc from the siphon on top of the fennel, and place a buckwheat crisp on top of the cheese.
Garnish with a piece of chervil.