In a bowl, mix 3/4 cup sugar, tapioca, butter, and lemon extract. Peel and core apples; slice (1/4 in. thick) into sugar mixture and mix to coat (you should have 8 cups apple mixture).
Scrape apple mixture into unbaked bottom crust in pan. Cover with top crust and flute edges (see notes).
Bake on bottom rack of a 375° regular or convection oven for 30 minutes. Meanwhile, in a small bowl, beat egg yolk with 2 teaspoons water to blend. Brush pie lightly with yolk mixture (save extra for other uses or discard), then sprinkle with remaining tablespoon sugar. Continue baking until filling bubbles in center (check through cutout or slits), 25 to 30 minutes longer. If crust browns too quickly (check 10 minutes after brushing with egg), cover pie loosely with foil.
Let pie cool on a rack at least 1 1/2 hours. Cut into wedges and serve, or chill airtight up to 1 day.
Servings Makes 8 servings
* Percent Daily Values are based on a 2,000 calorie diet. Your daily value may be higher or lower depending on your calorie needs.