Once the meat is tender, remove it from the pot and keep it covered with a plate so it doesn't dry out. Let the liquid in the pot keep simmering – you should end up with about half a litre. Take out the spice bag just before thickening with the roux. Melt about four tablespoons of butter.

In the melted butter, sauté the remaining two roughly chopped onions until nicely golden. Just before they're done, sprinkle in two to three tablespoons of cane sugar and let it melt.

Finally, stir in plain flour – enough to form a thicker paste, or roux. Mix vigorously for a moment, then whisk it gradually into the bubbling liquid in the pot the meat was braised in.

Stir thoroughly, whisking if needed, then add the tomato purée or canned tomatoes. Mix again and simmer gently for about 20 minutes.

Blend the simmered sauce until smooth with a stick blender, then strain and press it through a fine sieve. Give it one last taste and adjust the seasoning with a pinch of salt, sugar, pepper – whatever it needs.

One more trick turns this smooth sauce into something velvety: simply whisk a piece of chilled butter into the finished sauce once it's off the heat.

Return the meat to the sauce, warm it through, and serve.

Try adding a couple of cloves for extra depth – the sauce will taste a touch sweeter, but it's delicious! If you're making this sauce for meatballs, add the pan drippings from frying or baking the meatballs too – even the crispy bits of meat mixture will give the sauce extra character.