Cream butter and sugar in a mixer bowl until light and fluffy. Add eggs and mix well. Add sweet potatoes and mix well. Stir in evaporated milk, vanilla, salt, lemon juice and lemon zest. Pour into pie shell. Bake for 40 minutes at 375 degrees F.

I usually peel 2-3 sweet potatoes (called yams or red yams outside the South), cut them into 1-2" chunks, and boil them until they just start to get soft. Then strain and mash them for the 2 cups of mashed sweet potatoes. I prefer this in a graham cracker crust, but you can also make it in a regular crust. The lemon is optional, but I always use it rather than cinnamon or nutmeg so the pie doesn't end up tasting just like another pumpkin pie. This pie is good still slightly warm, or refrigerated. If you refrigerate it, it may split as it dries a little. Just top with whipped cream to hide the split.