While you prepare the dough, begin heating the lard (best flavor), shortening (less saturated fat but also less flavor), or vegetable oil (probably the healthiest alternative but if you're doing these for flavor, this is not the choice to make). An 8-quart stock pot is an appropriate size cooking container., Slowly start to heat melt/heat the fat over medium heat; you want it to reach somewhere between 365°F and 375°F before you begin to cook., Beat together the eggs, buttermilk, sugar and lemon oil or zest until light. In a separate bowl, blend together the dry ingredients., Melt the butter, but make sure it's not excessively hot. Quickly blend the dry ingredients with the wet and stir in the melted butter. The resulting dough will be quite soft, but if you keep your work surfaces well sprinkled with flour, you can deal with it it., Turn the dough out onto a floured surface, and knead four or five times to make it cohesive (a baker's bench knife helps here). Then, with a well-floured rolling pin, roll the dough out until it's about 1/2-inch thick., With a doughnut cutter dipped in flour (each time you cut), cut out doughnuts. Save the "holes" or re-roll them with leftover dough. Try to handle the dough as little as possible., When the fat is at the appropriate temperature (365°F to 375°F), lower three or four doughnuts into it. A slotted spoon is useful here. The doughnuts will initially sink to the bottom of the pot but will rise shortly. Give them a minute or so on one side, then flip them over and give them another minute., Flip them a third time and cook for another 30 seconds. Drain on paper towels (or brown paper grocery bags)., Store cooled doughnuts, well wrapped, at room temperature for a couple of days. Freeze for longer storage.