A stock question for British catering professionals When I was a child in the 1960s, we had a Co-operative restaurant that served the most incredible home-made broth. A few years ago, I visited a cafe, and their home-made soup tasted almost identical. Seizing my chance, I asked the proprietor what the ingredients were, assuming they had used lamb or beef bones as I have not managed to recreate this myself over many years of cooking.

I was surprised when they said "Just stock cubes". They weren't able (or willing to tell me) what brand they were, so I am assuming here that they are some commercial variety available in the the UK for the past 50 years or so. I know they are definitely not Knorr or any major supermarket own brand, so what could they be? The only way I can describe them is a very savoury, almost smokey taste that has an incredible depth of flavour. I have tried all the classic ways of recreating this flavour with homemade stock, bones etc. but have not come anywhere close. Both soups were a similar colour and consistency to Heinz lentil soup, and the childhood version definitely had bits of beef in it as I remember the very fine, well cooked shreds of meat.  

Any ideas what this mystery ingredient (or possibly technique) could be?
I buy tubs of Knorr stock powder from restaurant supply stores here in the uk, it's a different product from their cubes, and has a very different flavor, there's also a paste. It may be worth having a look at those. Knorr is the brand I see in the bulk quantities you'd typically see in a restaurant kitchen that you can get retail, other brands are not sold in the stores, like Brakes. 

You'll find many ingredients in stock cubes, powders and pastes to pack flavor into a small space. The commercial stuff I use has several flavor enhancers: E621 (Monosodium Glutimate aka MSG), E627 (Disodium guanylate) and E631 (Disodium Iosinate). Some have yeast extract in them. You could experiment with some MSG and Marmite to see if you can re-create that special flavor.