To prepare the hazelnut vinaigrette, combine vinegars, mustard, water, honey, shallot and lemon thyme leaves in a blender. Then, on low speed, slowly incorporate the hazelnut oil to emulsify. This vinaigrette can be stored in the refrigerator for up to one week.
For the Forbidden rice, combine rice, water and olive oil in a saucepan and bring to a boil. Reduce heat to a bare simmer for an additional 25 minutes or until all moisture is absorbed. Stir in olive oil and porcini paste (if desired); set aside.
Prepare an ice bath. Bring a pot of seasoned water to a rapid boil and add turnips, leeks and peas in separate batches, until just cooked through. (Times will vary – a pea may take as little as one minute and the turnip up to six minutes – be sure to taste each vegetable as you go.) Plunge blanched vegetables into the ice bath to arrest cooking. Pat each batch dry and reserve.
Preheat grill to medium high. Brush fennel slices and mushrooms with olive oil and grill vegetables to caramelize; set aside.
In a cast iron pan, toast eggplant and onions over medium high heat until soft to the touch. Allow to cool slightly, peel, slice and reserve.
To plate, divide rice between six warm bowls. Gently warm the vegetables in the oven and then toss in vinaigrette. Place a generous serving of vegetables over the rice, garnish with crushed hazelnuts and serve.