1. Using a soft brush, remove any dirt from the taro root. Then, peel it and pat it dry with a towel (do not wash it, or it will get slimy!).
2. Insert the knife into the root and break it into small pieces (we 'snap' it, so to speak). The secret is to break it, not cut it. In a pot, add the olive oil and sauté the onion for 4 minutes.
3. Next, add the taro root, the potatoes, and continue sautéing for another 4-5 minutes. Stir occasionally. Add the celery and the tomato paste. Stir the paste on the bottom of the pot so it releases its aromas.
4. Add the stock cube and pour in the water. Cover the pot, lower the heat, and boil for 25 minutes. Occasionally shake the pot (do not stir).
5. After 25 minutes, open the pot, add the salt, pepper, and pour in the lemon juice. Boil for another 5-10 minutes until the sauce thickens.
