In a large stockpot or casserole over medium heat, cook the onions and garlic, oregano and salt and pepper in the olive oil until the vegetables are translucent, about 10 minutes. Add the chopped carrots, diced potatoes, all the split peas and the chicken stock or water. Bring to a boil, then simmer uncovered about 45 minutes. Stir occasionally to make sure nothing sticks to the bottom. As the dried peas break down they’ll adsorb much of the liquid and the soup will thicken. Add a little extra salt and pepper to taste at the end and serve.
For an extra touch, you can sprinkle croutons on each bowl of soup. Enjoy!