I remember drinking weed tea on the terrace of a coffee shop in Amsterdam (leaves in a cup, then hot water upon it, like common tea). The waitress told us to let it simmer for quite a while, then to squeeze the leaves with the spoon. The effect was very weak. Note that chemically, making tea is a form of extraction (extraction in a solvent, water). The term "extraction" used in the law is wrong, as usual, "refining" or "concentrating" would be correct.