Preheat the oven to 180℃/170℃ fan /gas mark 4. Line a 900g loaf tin with baking parchment.
Heat oil in a frying pan over medium-high heat. Add onion and stir continuously. Cook for about 5 minutes, or until softened. Add the garlic and cook, while stirring, for another minute. Allow to cool slightly.
Place the onions, beef, oregano, breadcrumbs, and brown sauce in a large bowl. Mix well.
Add the eggs and beat until well combined.
Pile just under half of the mixture into the lined loaf tin and press level. Arrange the red pepper strips down the centre of the tin. Cover with the sliced mozzarella.
Spoon the remaining meat mixture on top and press down well. Cover with foil and bake for 1 hour.
Allow to stand for 10 minutes, then turn out and slice to serve.
Nutrition information is approximate (does not include seasoning with salt and pepper) and is meant as a guideline only.