Preheat the oven to 180°C (fan-assisted) or 200°C conventional. Line a 900g loaf tin with baking parchment, leaving an overhang on the long sides to help lift the cooked loaf out later.

Sweat the aromatics: Heat the olive oil in a large frying pan over a medium heat. Add the diced onion and cook for 5-6 minutes, stirring occasionally, until it turns translucent and looks glossy. You want it soft but not coloured. Add the minced garlic and cook for a further minute until you can smell its fragrance. Remove from the heat and let it cool for a few minutes.

Mix the meatloaf base: In a large mixing bowl, combine the turkey mince, cooled onion mixture, breadcrumbs, beaten eggs, tomato purée, Worcestershire sauce, dried thyme, smoked paprika, salt, and pepper. Use your hands to mix everything together gently. Stop as soon as it's combined; overmixing will make the loaf dense and tough. The mixture should feel soft and slightly sticky but hold together when pressed.

Shape the loaf: Tip the mixture into the prepared loaf tin. Press it down evenly, smoothing the top with the back of a spoon or a spatula. It should be level from edge to edge so it bakes evenly.

Make the glaze: In a small bowl, whisk together the ketchup, brown sugar, apple cider vinegar, and mustard powder until the sugar has mostly dissolved. The glaze will look a deep, rich red and smell tangy and sweet.

Bake and glaze: Place the loaf tin on a baking sheet to catch any drips. Bake uncovered for 30 minutes. Remove from the oven and spoon half of the glaze over the top, spreading it gently to cover the surface. Return to the oven for another 20 minutes. The glaze will bubble and darken slightly, looking sticky and caramelised at the edges.

Final glaze and rest: Spoon the remaining glaze over the top and bake for a final 5 minutes. The internal temperature of the loaf should reach 74°C if you're using a meat thermometer. The top will be a glossy, deep mahogany colour, and the edges will be slightly caramelised. Remove from the oven and let the meatloaf rest in the tin for 10 minutes. This is a crucial step—it allows the juices to redistribute, so your slices stay moist rather than crumbling apart.

Slice and serve: Using the parchment overhang, lift the meatloaf out of the tin and transfer it to a cutting board. Slice into 8 even portions. The slices should hold their shape neatly, with a tender, moist interior and a sticky, flavourful crust.