Just tried the Aldi herring in mustard sauce. Not a fan. The sauce was no good unfortunately. Aldi herring in tomato is decent though. Pretty good to just dump the tin into some pasta and mix.
Overall, I am finding I pretty much only want my tinned fish to be in olive oil, nothing else - and no other oil.
I have tried that one too, better than the mustard, not as good as the tomato sauce in my opinion. Still none are as good as just the Brunswick brand plain Kippers I reckon.