If you need small amounts of potting soil sterilized quickly, you can sterilize it in the microwave instead of sterilizing soil yourself in the oven.
Place two pounds of potting soil into a thick plastic bag (such as a freezer bag, not a thin “sandwich” type bag which can melt in the microwave. Place bag in microwave leaving the top open for ventilation. Microwave on high for two and a half minutes on high. Remove from microwave promptly and seal top. Allow to sit until cool, then use. You an keep the soil in the bag with the top closed for storing.
This method will not smell your house up quite as much as the oven method, but you can only sterilize smaller portions of potting soil ast a time. Remember, do not heat for longer that two and a half minutes or you can make the soil toxic.