You want to break open the cardamom pods first.  I simply set them on a cutting board and crush them open using the flat of a large chef's knife.

Add the water and sugar to a saucepan and turn the burner on medium-high. 

Stir until the sugar dissolves, and add the cardamom pods and little black seeds (it doesn't really matter when, I usually wait til the sugar is dissolved).

Once the bubbles start coming up indicating it's starting to boil, remove it from the heat and add the pinch of salt.  Let it sit for about half an hour to steep and cool.

Strain out the cardamom pods and seeds (I use a tiny mesh strainer), pour into a container, and refrigerate.  Should last a few weeks in the fridge.