I tried one of their 'Delux' joints of sirloin last week. They were going half price, so I got a 900g joint for something over £8.
It was absolutely delicious and completely melted in the mouth. Even a couple of days after cooking, it still tastes delicious and is extremely soft when you warm it up from the fridge.
I have no idea if the offer is over, but I'm off tomorrow to see if I can get another one.
At the moment, I'm also finding their cauliflowers to be the best. They taste nice but they're also big. The ones in Aldi and Asda are tiny once you cut off all the leaves they leave on to make them look big. Asda do extra large cauliflowers about the same size as a Lidl normal one, but for twice the price.
Lidl are also currently going bottles of Hardy's Stamp shiraz/cabernet sauvignon or Bin 53 Shiraz for £4.69, both of which are great for that price, especially with a sirloin roast! A couple of other supermarkets have subsequently put the Hardy's shiraz/cabernet sauvignon on offer for £5, but Lidl are still cheaper.
I also tried their white farmhouse loaf, and it's lovely. Though I only buy it if it's very soft and fresh. Some batches are a bit more dry and hard. They're 85p compared to 65p for an Aldi toaster loaf, or £1 for an 800g Warburtons loaf from Asda (which is more consistent than Lidl's farmhouse).