Prepare the steamer – Fill a steamer or large pot with water and bring it to a gentle boil.
Mix dry ingredients – In a bowl, combine flour, sugar, baking powder, and salt.
Add wet ingredients – Add milk, vegetable oil, and vanilla extract to the dry mixture.
Mix well – Stir until the batter becomes smooth without lumps.
Prepare cups – Pour the batter into cupcake molds or heat-safe cups, filling about 70%.
Add toppings – Sprinkle chocolate chips or fruits if desired.
Steam the cake – Place the cups in the steamer and steam for 12–15 minutes on medium heat.
Check doneness – Insert a toothpick; if it comes out clean, the cake is ready.
Serve – Let it cool slightly and enjoy warm.