1. Prep ingredients
Peel the sweet potatoes and cut into 2cm chunks. Finely chop the onion. Finely chop the tomato. Crush or finely chop 2 garlic cloves.
2. Make mash
Put the sweet potato in a medium saucepan of cold salted water and bring to the boil. Reduce the heat to medium and cook for 10 mins or until tender. Drain, then return to the pan and mash until smooth. Add 20g butter, season with salt and pepper and stir until combined. Cover to keep warm.
3. Start filling
Meanwhile, heat 2 tsp vegetable oil in a medium deep frypan over medium heat. Cook the onion, stirring, for 3-4 mins until softened. Increase heat to high, add the beef mince and cook, breaking up the lumps with a spoon, for 3-4 mins until browned. Add the tomato, garlic, curry paste and half the tomato paste* and cook, stirring, for 1 min or until fragrant.
4. Simmer filling
Add 125ml (½ cup) water to the beef mixture and bring to the boil. Reduce the heat to medium and cook, stirring occasionally, for 8-10 mins until slightly thickened. Add the spinach and 2 tsp soy sauce and cook, stirring, for 1 min or until the spinach is wilted. Remove the pan from the heat. Taste, then season with salt and pepper.
5. Grill pie and serve up
Preheat the grill to high (see Make it faster). Spoon the beef filling into a 1L (4 cup) baking dish. Top with the sweet potato mash and grill for 5-7 mins until golden. Divide the cottage pie among bowls and enjoy!
6. Make it faster
Short on time? Skip grilling the pie and simply serve the beef filling spooned over the sweet potato mash instead.