Scrub 3 potatoes, and place in a pot of cold water. Cover and bring to a boil. Once the water is boiling, stir in 1 teaspoon of salt. Remove the lid and reduce the heat to simmer. Every 5 minutes check if the potatoes are done with a fork. Once soft enough, remove and allow to cool on a plate for 10 minutes. Remove the peel and mash while still warm. Cover and chill for a minimum of 3 hours or use leftover mashed potatoes.
Scrub and peel 3 potatoes. Using a box grater, grate the potato over a clean kitchen towel. Wring the towel tightly to squeeze out the extra water over a bowl.
Place the grated potato and cooled mashed potato in a large bowl and mix together with your hand, then add the flour, baking soda, salt, black pepper, sugar, and mix well.
Add 1 tablespoon of bacon grease (or melted butter) and mix in well before pouring in the buttermilk. Stir to combine. If you want a thin batter, pour in more buttermilk to get the consistency you want for the batter. Let the batter rest for 20 minutes.
In a cast iron skillet, melt 1 tablespoon of bacon grease (or butter) over medium high heat until shimmering, pour in the potato batter, using a spoon to spread it around to get your desired thickness. Lower the heat to medium low. Cook 4 minutes each side for a ¼ inch thick pancake. Repeat with the rest of the batter. Irish potato pancakes take longer to cook then American pancakes because of the raw grated potato.
Boxty or Irish potato pancakes taste best when served immediately to keep their crispness. They lose their appeal when they are soggy. Serve with your choice of savory toppings, such as chives, bacon, poached egg, sausage and sour cream. (They're similar in taste to hash browns.)