In a medium size bowl combine the crumb topping ingredients with a fork or pastry blender until it resembles small crumbs.
Refrigerate while you prepare the apple filling.
Spray IP with non-stick cooking spray.
Add melted butter, lemon juice, vanilla, brown sugar, cinnamon and salt and stir to combine. Add apples and toss to coat. Pour in water.
Sprinkle crumb topping evenly over the apples.
Cook on high pressure (manual for 1 minute).
When timer beeps, turn the valve to quick release the pressure/steam. Start slowly to be sure only steam comes out, and then fully release it.
Optional: Spoon servings into oven-proof dish and broil for 1-2 minutes, to crisp the topping, if desired