Blend oats in a blender until flour-like. Combine oats and almond meal in a bowl. Add oil, vanilla extract, cinnamon, and salt; mix until crumbly. Add 1 tablespoon of water at a time, mixing after each addition. Continue until dough is smooth and comes together in a ball.
Turn dough out onto a sheet of waxed paper; flatten with the palm of your hand and shape into a thin circle. Transfer dough to a baking sheet. Spread 1 tablespoon of preserves on top.
Peel, halve, core, and thinly slice apples. Arrange on dough in an overlapping circle from outer edge to center.
Bake in the preheated oven until tart is golden brown with slightly darker edges, 15 to 20 minutes. Place on a cooling rack.
Combine remaining 1 tablespoon preserves and 1 teaspoon water in a microwave-safe bowl, and heat in a microwave until melted, about 10 seconds; brush over tart.