Lime and mint chiffon cake

So it's getting a bit hot in the UK (and I've got quite a few limes filling up the fridge that I had to use up), so I've decided to get put this together.

Ingredients

• 150g self raising flour
• 200g caster sugar
• 4 large eggs, separated
• 50g mint (stalk and leaves)
• 80ml vegetable oil
• 5 limes
• 50ml water
• 400ml double cream
• 80g icing sugar
• Blueberries and raspberries for decoration

1. Pre-heat oven to 170degrees C (150 fan)
2. Mix flour and 100g caster sugar together 
3. Boil mint stalks in 50ml water for 15-20 minutes over low heat
4. Remove stalks from water and let the water cool down to room temperature
5. Add vegetable oil, zest and juice from 3 limes, water and 4 egg yolks to the dry ingredients and mix well
6. Whisk egg white until foamy and gradually add 100g caster sugar to the egg white one tablespoon at a time until all the sugar has been added and the egg white forms stiff peaks
7. Add 1/3 of egg white to the cake batter and mix it in
8. Add the remaining egg white to the cake batter and very gently fold it in
9. Gently pour cake mix to an 18cm round cake tin
10. Bake for 50-70 minutes, the cake should rise well. Test with skewer and it should come out completely clean if the cake is cooked
11. Cool the cake upside down for 1 hour
12. Prepare filling by mixing cream with zest and juice from 1 lime and whisk until the cream is thick
13. Slice cake horizontally into 3 equal layers
14. Spread the cream between each layer and on the exterior of the cake
15. Decorate with the remaining lime, berries and leftover mint leaves