Place cowheel in a large pot and cover with water, boil until tender adding more water as needed. I highly recommend using a pressure cooker to cut down on the cook time. Pressure for 20-25 minutes.
Once cowheel is tender, remove from water and allow to cool before cutting into smaller pieces.
In a large pot over medium heat, add oil. When oil is hot add carrots, onion, scallion, garlic, thyme and pepper and sautee until the onions are soft, about 3 minutes. Add split peas, cowheel and 3 cups of the liquid that the cowheel was boiled in and an additional 4 cups of water and bring to a boil. Reduce heat and cover and cook until split peas are soft and dissolves into the soup, about 1 ½ hour.
*Dumplings can be added to the soup in the last 10 minutes, here are two dumpling recipes here and here
*Root vegetables such as sweet potatoes, eddoes or dahseen can be added to the soup