Preheat oven to 200°C.
Place the flour, icing sugar and salt in a food processor.
Add the butter and whisk into fine crumbs.
Transfer to a mixing bowl, add the nuts and stir in the egg yolk to bind.
Chill for an hour, then press into a 20 cm fluted flan tin lined with greaseproof paper.
Chill again for 30 minutes.
Bake the pastry blind for 15 - 20 minutes or until golden brown.
Remove from oven and leave to cool.
For filling, mix together the mascarpone, yoghurt and icing sugar.
Place half of the strawberries on the base of the tart shell.
Spread the filling over the top and garnish with the remaining strawberries.