To prepare the coulis:
Cut the kernels off the cob, reserving the kernels and cobs separately. Place the cobs in 11/2 quarts water in a stockpot. Tie the parsley stem, peppercorns, thyme sprig, and bay leaf in a piece of cheesecloth and add it to the pan. Bring to a simmer and cook for 30 minutes. Strain into a bowl through a fine-mesh sieve and return the liquid to the pan. Add half of the onions and two-thirds of the corn to the pan and simmer for 15 minutes. Pour the mixture into a blender, purée until smooth and strain into a saucepan. Bring to a boil, remove from the heat, and whisk in 1 tablespoon of the butter. Season to taste with salt and pepper and set aside.
To toast the corn:
Heat a nonstick sauté pan until very hot. Add 2 tablespoons of the olive oil and 2 tablespoons of the butter and cook for 15 seconds, or until the butter starts to bubble. Add 1/2 cup of the reserved uncooked corn kernels and sauté for 20 to 30 seconds, or until golden brown. Remove from the pan and drain on paper towels.
To prepare the filling:
Melt the remaining 1 tablespoon butter in a small saucepan over medium-low heat. Add the remaining onions and cook for 3 minutes, or until translucent. Add the curry powder and cook for 2 minutes, or until the curry powder becomes fragrant. Add the remaining corn, cook over medium heat for 3 minutes, and remove from the heat.
Heat the remaining 2 tablespoons olive oil in a medium sauté pan and add the mushrooms. Cook for 3 to 4 minutes, or until all of the liquid is evaporated. Add the garlic and thyme and cook for 1 minute. Remove from the heat and drain off any liquid in the pan. Coarsely chop the mushrooms and add to the corn-onion mixture. Stir in the parsley and season to taste with salt and pepper. Allow the mixture to cool to room temperature.
To prepare the ravioli:
Lay 12 of the wonton skins on a flat surface. Place a spoonful of the filling in the center of each wonton. Brush the edges of the remaining 12 wontons with the egg and place them, egg side down, on top of the filling. Firmly press together the edges of each ravioli, removing any air pockets, and completely seal the edges. Cook the ravioli in boiling salted water for 3 to 4 minutes, or until they float. Remove the ravioli from the water with a slotted spoon and drain thoroughly.
Reheat the corn coulis. Place 3 warm ravioli in the center of each plate and spoon the coulis over the ravioli and around the plate. Sprinkle the toasted corn and chive pieces around the plates.