1Melt your chocolate and margarine together in a glass bowl in the microwave for about a minute, stir for two minutes, and then put it back if you need to melt it some more.
2Add your sugar.
3Add four eggs, one at a time, whisking each time.
4Add vanilla, cocoa, and salt.
5Add the potato starch and mix it up.
6Pour the mixture into a greased pan.
7Bake at 350°F (180°C) for 35 minutes, or until set.
8Let cool.
9Lift the brownie out of the pan and cut into squares.