Step 1: In a bowl add butter, brown sugar and corn syrup. Microwave it for about 2 mins till it starts sizzling.
Remove it from microwave and add baking soda. Stir well.
Step 2: Put popped popcorn in a big bowl and add the butter sugar mixture. Mix well to coat all the kernels.
Step 3: Put a lid on top of the bowl and microwave for another 1 1/2 minutes. Shake the bowl well.