Preheat your oven to 350°F (175°C). Peel and core the apples, then slice them into thin wedges. Toss the apple slices with sugar and lemon juice, and spread them evenly in your baking dish.
In a large mixing bowl, combine the rolled oats, brown sugar, all-purpose flour, and sea salt. Use a pastry cutter or your fingers to cut in the cold, cubed butter until the mixture resembles coarse crumbs with some larger clumps.
Sprinkle the crumble evenly over the apples, pressing lightly so some of the topping contacts the fruit and adheres better during baking.
Place the baking dish in the preheated oven and bake for about 40 minutes, until the topping is golden brown and the apples are bubbling around the edges.
Remove the crisp from the oven and let it cool slightly; this helps the juices to thicken and prevents over-sogginess. Drizzle caramel sauce over the warm crisp or individual slices before serving.
Scoop the warm apple crisp onto plates, ensuring some of the caramel and crunchy topping make it onto each portion. Enjoy the contrasting textures and fragrant aroma.
