Peel the sweet potatoes and cut into 4cm chunks. Finely chop the onion. Crush or finely chop the garlic. Coarsely grate the carrot. Crumble 1 stock cube* into a heatproof jug, add 180ml (¾ cup) boiling water and stir to dissolve.
Step 2 — Cook sweet potato
Put the sweet potato in a medium saucepan, cover with cold salted water and bring to the boil. Reduce the heat to medium and cook for 12-14 mins until tender. Drain and return to the pan, then stir over low heat for 10-20 secs until any water is evaporated (drying the sweet potato helps to make fluffy mash). Remove from the heat.
Step 3 — Cook beef mince
BEEF MINCE OPTION While the sweet potato is cooking, heat 1 tbs olive oil in a medium deep frypan over medium heat. Add the onion, garlic and carrot, season with salt and cook, stirring, for 5 mins or until softened. Increase the heat to high, add the beef mince and cook, breaking up the lumps with a spoon, for 3 mins or until browned.
Step 4 — Make sauce
Add half the tomato paste* to the mince mixture and cook, stirring, for 1 min. Add the tomatoes, stock, Italian seasoning and ½ tsp sugar and bring to a simmer. Reduce the heat to medium and cook, stirring occasionally, for 8 mins or until the sauce is thickened. Taste, then season with salt and pepper. Spoon into a 750ml (3 cup) baking dish.
Step 5 — Mash sweet potato
Preheat the grill to high. Add 15g butter to the sweet potato and mash until smooth. Season with salt and pepper. Spoon the sweet potato mash over the mince mixture and spread evenly, creating a textured finish using a fork (this creates a a crisp crust). Put the pie on an oven tray and grill, checking regularly, for 6 mins or until the top is lightly browned.
Step 6 — Get ready to serve
Meanwhile, combine 2 tsp extra virgin olive oil and 1 tsp balsamic vinegar in a large bowl and season with salt and pepper. Add the rocket and toss to combine. Serve the pie at the table with the dressed rocket.