In a bowl mix rice flour, almond flour, potato starch, pinch of salt and grated lemon peel
Add the margarine/vegan butter and the limoncello, mix everything with a spoon until you get big "crumbs" of dough
Move the dough to the work surface and work the crust dough with your hands, until you get a uniform, compact ball of dough
Cover it in wrapping plastic and let it rest in the fridge for 1 hour (or 30 minutes in the freezer)
Pre-heat the oven at 160° C / 320 F
Take the dough out of the fridge/freezer, cut it into parts (if you are making small tarts), slightly grease the molds and push/spread the dough with your fingers directly into the molds (or the whole dough into the tart pan, if you make a single big one)
The tarts should be more or less half centimeter thick
Pinch the tarts base with a fork and bake them for 20-25 minutes (you can bake for another 5 minutes in grill-mode to get a more golden top
Remove the tart bases from the oven and let them cool down completely