Preheat oven to 240°C Line an oven tray with baking paper.
Cook sweet potato in a medium saucepan of boiling water for 10 minutes or until tender. Drain well. Transfer to a heatproof bowl. Use a fork to mash until smooth. Set aside to cool in bowl.
Cook carrot and potato in a medium saucepan of boiling water for 5 minutes or until tender. Drain well. Set aside for 5 minutes to cool slightly.
Add carrot mixture, peas, corn, cheese and 1 egg to sweet potato and stir to combine. Season with salt and pepper.
Use a 12cm-diameter pastry cutter to cut 12 discs from pastry sheets. Spoon vegetable mixture evenly among pastry discs. Brush edges of pastry lightly with remaining egg. Fold pastries in half to enclose filling. Use fingertips to gently press together to seal.
Place on the lined tray and lightly brush with remaining egg. Sprinkle with sesame seeds.
Bake in oven for 15 minutes or until golden brown and cooked through. Remove from oven and set aside to cool.
Once completely cooled, wrap in baking paper, and store in the fridge ready for the lunchbox.