This slice is all about tang and texture. The rhubarb-lime jam
is refreshingly tart and cuts through the sweetness of the
meringue, which means you can go back for seconds or even thirds.
This recipe makes about 20 pieces.
For rhubarb-lime jam, stir ingredients except raspberries in a saucepan over medium-high heat until sugar dissolves, then simmer, stirring occasionally, until mixture is thick and jammy (10-15 minutes). Remove from heat and stir in raspberries. Transfer to a container and refrigerate to chill (1-2 hours). Jam can be made 2-3 days ahead.
For shortbread pastry base, preheat oven to 180C. Line a 20cm x 30cm slice tin with baking paper, allowing sides of paper to overhang. Beat butter, sugar and rind in an electric mixer until light and fluffy (2-3 minutes), scrape down sides of bowl, then beat in yolks to combine. Stir in flour, baking powder and a pinch of salt to form a soft dough, then press evenly into base of prepared tin. Dock with a fork and bake until golden and crisp (10-15 minutes).
Whisk eggwhite and a pinch of salt in an electric mixer until soft peaks form. Gradually add sugar and whisk to soft peaks (2-3 minutes). Whisk in vanilla, then fold in coconut.
Spread rhubarb-lime jam evenly over pastry base, then spread coconut meringue mixture over and bake until golden brown (10-15 minutes). Cool completely in tray, dust with icing sugar, then cut into bars and store in an airtight container until required. Slice will keep for 1-2 days.