Preheat the oven to 150°C/300°F. Use a pencil to draw a 26cm diameter circle on a sheet of baking paper that’s the same size as your large baking tray. Then draw a 15cm diameter inner circle inside the centre of the larger circle, this is the outline of your wreath. Turn the paper over and place on the large baking tray.
Make the meringue in a large clean bowl. Whisk the egg whites and salt into stiff peaks. Slowly add the sugar, a third at a time, whisking well between each addition until the mixture is stiffened and shiny.
Sprinkle in the cornflour, vinegar and vanilla extract, then fold in gently with a metal spoon.
Spoon the meringue in between the 2 circles on the baking paper to make the wreath (ring shape). Smooth the edges with a palette knife and ensure the top is wide enough so you can add the topping later. Make a dip to the top (all round) for the topping to sit in. Make upward strokes with the palette knife all the way round the outside of the wreath.
Put in the oven and reduce heat to 120°C/240°F. Cook for 1½ hours until pale brown but a little soft in the centre. Turn off the oven, leave the door ajar and allow it to cool completely.
To make the filling, whip the cream in a bowl with vanilla seeds and lemon rind until thickened and just holding its shape.
To serve, gently peel the parchment paper off the Pavlova and carefully transfer to a serving plate or cake stand. Pile on the cream mixture and arrange the fresh fruit and mint on top. Serve straight to the table and cut into slices.