1) Place the olive oil in a 4-litre stockpot on a medium heat, and saute the onions, garlic, oregano, salt and pepper until the onions are translucent, for 10 to 15 minutes.
2) Add the carrots, potatoes, split peas and the chicken stock. Bring to the boil, then simmer uncovered for 40 minutes.
3) Skim off the foam while cooking. Add the remaining split peas and continue to simmer for another 40 minutes, or until all the peas are soft. Stir frequently to keep the solids from burning on the bottom.
4) Season with salt and pepper to taste. Serve hot.