Preheat the oven at 180°C (350°F). In a large bowl, add flour, oats, sugar and vanilla.
Zest the lemon and orange into the large bowl. Then keep the lemon and orange aside (we’re going to need it)
With clean hands, mix the crumble topping.
Wash the frozen or fresh berries and put into a baking dish. I used a (20x20cm). Then add the tbsp of sugar, juice half the lemon and orange (that we’ve put aside) Mix the mixture carefully.
Cover the berries with crumble topping. And bake it until the topping is golden for around 20-25min.