Preheat oven to 350ºF/175ºC.
Make the flax eggs by combining flax meal and water and let sit to gel for about 10 minutes.
Meanwhile, cream the margarine and sugars together until creamy. Stir in flax eggs and vanilla extract, then sift in flour, baking powder, a pinch of salt.
Add rolled oats and mix until incorporated.
Spoon out heaping tablespoons (my scoop is 1.5 tbsp) of batter onto a lined baking sheet, leaving at least 2 inches between each ball of dough. Bake for 8 minutes, or until the edges are barely golden. You want to underbake these cookies so they're extra soft. Remove from oven and let cool on a wire rack. Repeat until all batter is used up.