Stir-Fried Chicken

We keep hearing that it's easy to prepare stir-fry dishes. You just keeping stirring the ingredients until they're cooked,... supposedly.
The thing is, what do we use to flavor the dishes ?

My mom sent me a Chinese cookbook - it's more of a pamphlet, really - and this gave us a starting point in terms of the sauce.

For this chicken-stir fry dish, we used the following:

Skinless & boneless chicken thighs, cut into strips
1 head of broccoli florets (did not know that the stem is edible so I threw it away, argh!)
1 carrot, sliced
quail eggs
2 cloves garlic
1 tsp grated ginger

sauce:
2 tbsp oyster sauce
1 tbsp lite soy sauce
1 tsp cornstarch, dissolved in 2 tbsp water
1 tsp sugar

1. Blanch the vegetables - broccoli and carrots.
2. In a wok, saute the garlic and the ginger in hot oil.
3. Add the chicken and stir around until chicken in cooked.
4. Pour in the sauce and then add the vegetables and the quail eggs.
5. Let the sauce boil and thicken.
6. Serve