Preheat oven to 350 F.
For crumble topping, in large bowl, mix to combine flour, oats, flaxseed, cinnamon, and salt. Stir in oil and honey or syrup, stirring until mixture is fully incorporated and mixture is tacky.
For filling, in large bowl, mix apples or pears, berries, water, and lemon juice until fully combined. Tip fruit into 10-inch round or 8 x 8-inch baking dish or cast iron pan, distributing fruit filling evenly.
To assemble, crumble topping over fruit filling, pressing down gently to encase fruit. There may be extra crumble topping, which you can freeze for another crumble or crisp
Bake for 40 to 50 minutes, until fruit is bubbling and topping is beginning to brown. Serve warm or chilled with yogurt or a splash of milk, if desired. Once cool, cover, and refrigerate—it lasts for about a week. Reheat single servings in low oven, if desired, or enjoy cold.