1: Prepare the udon noodles according to packaging instructions.
2: Heat the peanut oil in a pan and sauté the onion until translucent.
3: Add the chicken to the pan and cook until browned.
4: Mix in the broccolini and cook for a few minutes.
5: Add the cooked udon noodles and tamari to the pan.
6: Toss everything together and serve hot.
