Heat the olive oil in a large saucepan or pot over medium heat. Add the celery, onion, carrots, and garlic and sauté for about 5 minutes, until the vegetables are soft. Add the water or stock, the potatoes, ham hock, split peas, and bay leaves. Turn the heat down to low and simmer for about 40 minutes, until the peas have turned very soft and begin to lose their shape, leaving you with a thick soup. (Thin out with more water or stock if you prefer a thinner consistency.) Remove the ham hock, shred the meat clinging to the bone, and add back to the soup. Discard the bay leaves. Season to taste with salt and pepper, plus a few shakes of Tabasco, if you like.