Slowly!
and ignore the amounts of water on the packet. I mix it with a tiny bit of hot water into a paste, then add very gradually, stirring and mashing up any lumps against the side of the bowl. Makes it a much better consistency. Then I microwave for 40 seconds, take out and stir stir stir, and add a touch more water if it's looking too dry, then back in for the remaining 20.
First time I made it I followed the packet instructions (it used to have instructions on) and ended up with an inedible bowl of wallpaper paste! :jelous: The above is based on long experience. It still tastes a bit weird/far too sweet IMO but it's hot and filling for breakfast and reasonably porridge-like in consistency.