On a dry pan, shortly roast pecans and sesame seeds. Let them cool down and then finely ground them in a food processor.
Beat the eggs with the sweetener, salt and citric acid. Add orange zest and continue beating for 5 minutes. Slowly pour melted butter.
Now add rum, vanilla extract, raw cacao powder and psyllium powder. When it unifies, add the ground nuts and seeds spoon by spoon.
Slowly start pouring sparkling mineral water. If your batter gets too liquid, add a tablespoon of coconut flour.
Line a 20x30 cm (approximately 8x12-inch) pan with parchment paper and pour the batter in. Bake it in the oven at 170ºC (340ºF) for 30 minutes. After it's baked, let it cool down totally and cut it into 2 pieces. (long side)
For the mousse, use softened butter that you kept overnight at room temperature. Beat it with the powdered sweetener for at least 10 minutes. Add mascarpone and sour cream at room temperature and keep beating. In the end, slowly add orange bloom water spoon by spoon. Keep the mousse in the refrigerator until your cake is totally cold.
Slice the strawberries. Place the first layer of your cake on a long platter and then spread some of the mousses on it. Add sliced strawberries and some more mousse on top.
Cover with another layer of cake. Finish by covering all the cake with the rest of the mousse and decorate with strawberries, almond flakes and cacao nibs. Serve after the cake has been chilled for at least 2 hours in the refrigerator.