Sous Vide diced beef @ 64ºc for 48hrs

This is frozen cubed beef of dubious origins. Sainsburys claims that this is British and I have to take their word for it. I made a curry paste from roasting some spices (cumin, black onion seeds, mustard seeds, cardamom  cloves, cinnamon, star anise, bay leaves and probably others) and mixed it in with the frozen beef before putting in the bag to marinade for a couple of days. Cooking at 64 for 2 reasons. 1, I think this meat will benefit from the slightly higher temps because it's a bit ropey, 2, I've got the brisket in at the same time and I want to cook the brisket at 64.
I made a curry sauce and tried to fry the beef to add some flavour. The frying didn't work as the marinade made it too wet and the beef was too flaky to hold together. So I just put it in the curry. The beef wasn't bad, there weren't many really chewy bits, and it was juicier than the slow cook method. I think the biggest lesson here is that the cheap frozen beef from Sainsburys is rubbish. I'll try some chuck steak from the butchers in the same way.