Start by mixing the flour, the rice flour, the baking soda, the salt, and the sugar in a bowl. Then, add in the soda water and the lager. Mix the ingredients until they are well blended, but be careful not to over mix the batter because a heavy batter will be noticeable on your fish.
In a large pan, heat the olive oil, and then sauté the potatoes in the pan over medium-high heat for about five minutes. When the potatoes are cooked enough, they will be a beautiful golden brown color. Add about half of the parsley and garlic mixture to the pan as well as a pinch of sea salt. Continue to cook the potatoes for about two more minutes. Make sure to stir the potatoes continuously so that they do not stick. Then, add the butter and the remaining parsley and garlic mixture.
Zest a bit of lemon over the potatoes and allow it to flavor the potatoes for about a minute. Remove the potatoes from the heat, season with more sea salt if desired, stir in the seasoning, and enjoy.