Wash brussel sprouts and trim the ends. Then thinly slice them in the food processor using the slicing disc. If you don't have a food processor, you can chop them by hand, but try to keep the slices as thin as possible.
Peel and mince the garlic and ginger, then chop the green onions. Note--if you choose to make shrimp with this dish, chop all the garlic, ginger, and green onions at the same time and separate them.
Open the two ramen noodle packs and discard the seasoning packets. Break apart the noodles into ½-inch pieces. Then heat a frying pan to medium-high heat (without oil). Add the noodle pieces in a single layer and toast them for about 5 minutes or until golden brown, stirring frequently so they don't burn. Remove the noodles from the pan.
In the same pan, toast the sesame seeds in a single layer for 5 minutes or until golden brown, stirring frequently. Remove the sesame seeds from the pan.
Heat the vegetable oil over medium-high heat in the frying pan. Then add the garlic, ginger, and green onions and sauté for 1 minute. They will become very fragrant.
Add the soy sauce, sesame oil, oyster sauce, and sugar to the pan. Stir until incorporated.
Then add the sliced brussel sprouts to the frying pan, stirring to evenly coat them in sauce. Sauté for about 8 minutes, stirring frequently, until the brussel sprouts are soft but not mushy.
Remove from heat. Stir in ramen noodle pieces and top with sesame seeds. Serve with chili sauce or sriracha if desired.