Preheat the oven to 175 ° C. Line a muffin tin with paper liners. Mix the butter, oil, sugar and egg until creamy. Stir in the vanilla pulp. Mix the flour with baking powder and salt and stir in alternately with the milk. Mix the strawberries with 2 teaspoons of flour and fold in. Fill the muffin cases with the batter and bake for 20 minutes. Do the chopsticks test. Let the cupcakes cool completely.
Mix the butter and salt until creamy. Stir in the strawberry jam and vanilla sugar. Gradually stir in the powdered sugar until you have a creamy pink buttercream. Pour the cream into a piping bag and spread over the cupcakes. Garnish each cupcake with a fresh strawberry and serve.