measure the desired quantity of media powder you want with a sensitive scale, ex: 4g of Sampleinside a heat resistant glass bottle with a lid with proper volume (size 250ml).

add the water you need, preferably distilled but tap water works fine for me, ex:100mL.

close the lid tightly to create pressure, and mix by shaking in your hand for 0h 0m 30s until the powder is dissolved.

put the media in the microwave n the highest degree for 0h 3m 0s, stop the microwave if you see bubbles appearing, let the bottle rest for few seconds then continue the process.

you may need an extra minute to make sure everything is correct, the media will look yellow and transparent.

take out the bottle with the media and let it cool under the flow of tap water, be sure to rotate the bottle under water until it becomes easy to touch with your hand, that means it reached 60-65°C.

sterilize the bottle by rubbing alcohol on it, and take it inside the laminar flow hood.

add your desired antibiotic like ampicillin ampicillin  ( 10µL ) to the media and shake inside the hood gently to spread it.

pour the media inside petri dishes, about 10-15mL is enough, then wait for about 0h 15m 0s until it cools off and solidify.

culture on your plates containing the sterilized media with the microwave method, then close the plates and place them in an incubator 37°C to grow your culture for 16-24 hours.

you can visually see the solid LB agar plates with grown cultures and no pollution of other bacteria.

i also tried a liquid LB broth and it gave good results with no pollution with very good growth.