Preheat the oven to 365 degrees.
Add the canola oil to a medium-sized pan and heat over medium-high. Add the oxtail and sear on all sides until nicely browned. Remove the oxtail from the pan and set aside. Add the vegetables to the pan and cook for 2-3 minutes, until they become soft. Add the tomato paste, garlic, thyme, and rosemary. Add the oxtail back into the pan and cover with the veal stock. Bring to a boil, cover, and place the pan in the oven.
Cook the oxtail for 3 ½ hours, or until the meat falls off the bone. When the oxtail is done, remove the meat from the bones, shred, and set aside. Strain the cooking liquid and reduce by ½. Add the shredded oxtail back to the liquid and season with salt and pepper to taste.
Fill each wonton wrapper with about 1-2 tablespoons of the oxtail mixture.
To make the sauce, add the chicken stock, foie gras, and butter to a saucepot. Reduce until the liquid reaches a thick, nape consistency (it will coat the back of a spoon). Add the port wine and reduce to a thick glaze.