1. Cut potatoes into 1-inch squares.
2. Cut carrots into half-moon shape.
3. Slice onions.
4. Cut tofu into 12 pieces.
5. Drain and wash shirataki noodles. Cut them in half.
6. Heat the vegetable oil in a medium saucepan over medium-high heat. Cook potatoes, carrots, and onions for 2 minutes. Add shirataki noodles.
7. Add water, oyster sauce, soy sauce, sake, mirin, and sugar.
8. Let it cook for 10 minutes and gently add Tofu.
9. When the potatoes become almost ready, add string beans.