Combine apples with just enough water to prevent sticking in a large stainless steel saucepan. Bring to a boil over medium-high heat. Reduce heat and boil gently, stirring occasionally, for 5 to 20 minutes, until apples are tender. Remove from heat and let cool slightly, about 5 minutes.
Transfer apples, working in batches, to a food mill or a food processor fitted with a metal blade and purée until smooth.
Return apple purée to saucepan. Add sugar, if using, and lemon juice. Bring to a boil over medium-high heat, stirring frequently to prevent sticking. Maintain a gentle boil over low heat while filling jars.
Ladle hot applesauce into hot, clean jars leaving 1/2 inch headspace. Remove air bubbles. Wipe rim. Center lid on jar. Apply band until fit is fingertip tight.
Process jars in a boiling water canner for 20 minutes. Remove jars and cool. Check lids for seal after 24 hours. Lid should not flex up and down when center is pressed.