The rich nature of portobello mushrooms makes this a hearty start to your fall meal; the pleasant bitterness of the Rapini plays nicely with the crisp earthiness of celeriac. 

Preparation

Dehydrate the celeriac at 105°F for 12–14 hours.

Chop the broccoli rabe into ¼-inch pieces and dehydrate at 105°F for 12–14 hours.

After degilling the mushrooms, slice them, paper thin, by cutting off the overhanging edges, and slicing from the middle outward on a heavy bias.  Then turn the mushroom 180 degrees and repeat the process.

In a shallow non-reactive container, mix the thyme, garlic, vinegar, lemon juice, water, olive oil and salt, and pack the mushroom, eggplant, and celery root into the container, making sure to press down firmly in order to submerge the ingredients.  Refrigerate and allow to marinate for at least 8 hours, but preferably overnight.

Line a 6"-x-2" terrine mold or loaf pan with plastic wrap, allowing for some overlap to hang over both sides.  Layer the marinated vegetables, starting with the mushrooms, then the eggplant, then the celery root.  Repeat this until the terrine is filled to the top, pressing down firmly after adding each layer.  Fold the remaining plastic wrap over the top, sealing tightly, and weight it; you can use a can of soup, or even an aluminum-foil-covered brick for this.  Refrigerate and allow to set for at least 8 hours, but preferably overnight.

Prior to serving, make the Broccoli rabe purée by combining the dehydrated broccoli rabe, water, lemon juice, olive oil, orange juice, agave, and shallot in a blender and process until completely smooth.  Add salt and pepper to taste.

Take the weight off the terrine and flip it out onto a cutting board.  Using a sharp knife, cut into ¼-inch slices (leave the plastic wrap on while cutting); this will make it easier to keep it together.  Serve with a generous portion of broccoli rabe purée.