Chill 4 salad plates. Preheat the oven to 250 degrees F.
In a medium sized bowl add the mushrooms, diced garlic, 1/4 cup extra-virgin olive oil, 1/4 cup balsamic vinegar, salt and pepper, mix all ingredients together until mushrooms are well coated. Place mushrooms, bottoms down, on a sheet pan, and roast in the oven for 45 minutes or until sweet, juicy, and tender. Remove from oven and dice. Meanwhile, Reduce the remaining 1 3/4 cups balsamic vinegar to a sweet glaze over low heat in a small saucepan.
Cut the sweet onions in quarters, then slice the onion into very thin julienne. Make sure you slice them so the onion slices do not stick together. Shock the uncooked onions in an ice bath for 4 minutes, strain the onions from the ice bath, set aside.
Mix the peppercress and baby lettuce together in a large bowl and set aside.
Season shrimp with salt and pepper and sear in olive oil in a hot pan. Set aside.
Using a small squirt bottle, or any small plastic container that will withhold a strong shake, add the Banyuls vinegar, mustard, lemon juice, salt, and pepper. Shake for 1 minute, until all is well mixed and salt has dissolved. Add the grapeseed and canola oil and shake again. Add the tomatoes, chives, shallots, haricots verts, and the shrimp to the lettuce mixture, and mix gently and slowly. Add the vinaigrette to lightly coat the coating to all the ingredients. Using chilled salad plates carefully place the salad in layers forming a nice small peak. Garnish with balsamic syrup and serve.