Peel, core, thinly slice and cut the apples into roughly bite-sized pieces. Place them in a large bowl and toss with the granulated sugar and lemon juice. Set aside to draw out moisture for at least five minutes.
In a large pan over medium heat, melt together the butter, brown sugar, vanilla, cinnamon, salt, and ¼ cup of water.
Keeping the heat at medium, stir in the prepared apple slices, including any liquid from the bowl. COVER with a lid and cook, stirring occasionally, for about 6 minutes, or until slightly softened and fragrant.
In a small bowl, stir together the 2 tablespoons of cornstarch and 3 tablespoons of water to make a thin slurry.
Remove the lid, and add the cornstarch mix to the pan over the same heat while stirring. Keep stirring and bring to a light boil. Cook uncovered, stirring constantly, until thickened, about 1 minute more.
Remove from the heat and cool slightly before using in a pie, serving over ice cream, or canning.
