This is a dish I used to make frequently whenever I needed to cook something fast and didn't have much time to shop. The only fresh ingredients needed are the chicken and udon (Japanese thick rice noodles): everything else - onions, garlic, chilli sauce and seasonings - are staples in my kitchen. I use sriracha chilli sauce, which, varies slightly in flavour from brand to brand, but usually has a good balance between spicy, sweet and vinegary. You might need to adjust the amount of other seasonings according to the spiciness of the sriracha.
2 packs (100 grams each) udon noodles
20ml cooking oil
1/2 a medium-sized onion, sliced
2-3 large garlic cloves, sliced
3 boneless chicken thighs, cut into bite-size chunks
About 10 grams oyster sauce