Place the flour, sugar, and salt in a large bowl and mix together.
Keep the butter as cold as you can.
Cube the butter and spread it out over the top of the flour mix. Add in the lard.
Cut in the butter and lard with a pastry cutter, two knives, or your fingers.
Once it is cut in and the dough is about the size of small peas, add the vinegar and beaten egg. You can mix with a spoon or, like I do, continue with the pastry cutter or fingers.
Last, add in the very cold water. (I measure it out and then add a few ice cubes to it.) Pour most of the water in but not all at once. You may not end up needing it all.
Work the dough together, but do not over mix. Pat it all into a ball. It should not be too sticky, but should easily stay together.
This is where I separate it into 2, 3, or 4 sections depending on what I'm planning to do with it. Make a ball, flatten it, and wrap in wax paper to put in the fridge for 30 min or so.
You can stop at this point if needed, and leave it in there for a few days before you do anything else with it. Add to a ziplock bag if not using right away.
After the dough has rested in the fridge, take it out and let it sit for a minute while you flour the surface you will work on. Try to handle the dough as little as possible while rolling it out. It is ok if you see chunks of butter while rolling it out. That is what makes it so flakey.