Place the flour, instant yeast, sugar, and cooking oil in a mixing bowl. If you are using a stand mixer, use a dough hook attachment. Gradually add in milk or water. You may need more than 150 ml most likely (or not). Add more teaspoon by teaspoon until the dough comes together and continue to knead for 5 minutes.
Make the dough by hands:
If you are kneading by hands, mix until you get a rough dough (it's not going to be smooth yet). Cover and rest it for 15 minutes. Then go back and knead it. You'll be surprised by how easier it is to knead it now. Knead until the dough is smooth and pliable, about 10-15 minutes. At any point during kneading, you can always stop and rest the dough if you find it hard to knead. This is to relax the gluten. Then go back to knead again and you'll be surprised by the difference it makes by just resting the dough before kneading again. It's easier on you too.
Pinch of about 20 gr of the steamed buns to make the piggies' snouts and ears. Wrap it with plastic wrap to prevent it from drying out. Drop the red food coloring on the rest of the dough to make a pink color and continue to knead until the color is even
Use the white dough that you pinch off earlier and make 32 pigs' ears and 16 snouts. Roll them into rounds and flatten to shape into flat pigs' ears and use a toothpick to make two depressions on each snout. Place two black sesame seeds for the eyes
If you choose to draw the eyes with an edible marker, do so only after the buns are steamed because the color may bleed a little bit when it's steamed
Let the dough rise at room temperature. If it's winter where you are, you can use your oven "bread proof" function to let them proof in there, or simply turn on your oven to lowest temperature and then turn off and after 15 minutes, place the shaped buns in there to let them proof. They won't necessarily double in size, but at least puff up to about 50% of original size. Do not overproof your dough
Most likely your steamer won't be able to accommodate steaming all buns at one go. You may need to steam in 2-3 batches, which means, the rest of the batches will sit longer and continue to proof while waiting for the steamer. Not good for the buns! Here's what you can do: Make sure the cover them with plastic wrap and then place them in the refrigerator to slow down the yeast activity or halt it all together until they are ready to be steamed
Bring the water in your steamer to a boil. Wrap the lid of your steamer with a kitchen towel to prevent moisture dripping back on the steamed buns as this will create "burn" spots
LOWER THE HEAT TO MEDIUM. Place the buns in there, leaving about 1-inch space in between. Cover with a lid but leaving it about 1/4-inch gap for some steam to escape. Steam on medium heat for 15 minutes. This is especially important if you see that you have overproof the steamed buns (the steamed buns have doubled in size and they have widened to the side). As long as you steam them like this, the buns will not wrinkle and collapse later when you take them out from the steamer
After 15 minutes, turn off the heat. DO NOT OPEN THE LID of the steamer. Let the buns sit there for 5 minutes like this. The buns will not sink or wrinkle due to the sudden change in temperature
If you make extra and plan to store the cooked steamed buns, place them on a baking sheet, not touching each other, and then put the entire tray inside the freezer for about 1 hour. They will harden, but not completely frozen yet. Transfer to a freezer bag and they will not stick to each other anymore. Try not to keep for more than 1 month
They can go straight from freezer to steamer when you ready to eat them. Steam on high heat for 5 minutes and they are as good as new
You can use active dry yeast, but make sure to rehydrate the yeast until it's foamy in warm water/milk and 1 tsp of sugar (not all 3 teaspoons) before mixing into the dough. You can add the rest of the sugar when mixing the dough later
You can also replace all 300 gr of all-purpose flour with cake flour or premixed Hongkong/Vietnamese bao flour and omit the wheat starch/corn starch.