1. Clean the oyster shells well. You must remove all the sand and dirt. Malaysian use the sauce to put on their rice. Use a brillo pad or wire brush to scrape all the crud and dirt from the shells. I have seen videos of Thais use shoots of lemongrass and ram it up and down in a bucket full of clams.
2. Cut the lemon grass into 1-inch strips. Then use a knife or mallet to break them open. Lemon grass has a tough sheaf surrounding it.
3. Saute the lemon grass, garlic, chilis, and curry leaves with olive oil in a wok for several minutes. Add the clams, mix, and cover for five minutes.
4. Sprinkle soy sauce and mix. Then mix the corn starch with a half cup of water, and add it to the clams. Keep mixing and then cover. Wait another five minutes.
5. Check the sauce. If the sauce is still watery, add another half cup of water with more corn starch. Once the sauce thickens, add oyster sauce and mix.
6. Cooking the clams should not exceed 15 minutes. Otherwise, the meat toughens. Add the oyster sauce towards the end.
Tip: Malaysians add plenty of chilis to their food. If you do not like spicy food, just add one chili. I am not sure how the clams taste withhout the chilis.