Marzipan, not cornflour as its a grain (maize). Sometimes, Arrowroot, but usually nothing!
For things like chilli or mince type recipes I will spoon out the liquid near the end of cooking, put in a frypan and reduce it down, then add back to the meat, this thickens the sauce a little, and adds flavour but really you just a adapt to NOT having lots of thick sauces on everything after a while. You have "juices" instead!
For a luxury touch, say with Sunday roast, I reduce the juices then stir in double cream, spoon a little bit on each serving of meat, it's very rich, a garnish to the meat really.
Sauces can add a lot of sugar/carb without you really noticing... Which can contribute to hunger and carb craving later in the day (especially if you ate just starting this woe and your body has not yet adjusted to the new reality
!
So tomato based sauces for example- may have huge amounts of sugar in them if you buy ready made (some may be 25%carb, or higher!) whereas a carton of passata (ingredients, tomato, salt) is about 5g carb per 100g- a huge difference. But even then, good idea to use less sauce than you would have before.
This woe is not necessarily about being "low carb" (although it is very carb carb compared with the standard diet {which has crazily high amounts of carb!}), but for weight loss, you do want to watch carbs carefully.
The easiest "rule" to keep in mind is "eat things with 5g or less of carbohydrate per 100g. Anything higher than that, ie sweet potato, be very careful with your amounts... I would have one small, or half a larger, sweet potato per serving
, it seems odd at first, not to have a big pile of stodgy stuff, but your tastes do adjust pretty fast, honestly!