To not want him to complain in restaurants?

Can't see that going down well.
Order £30 bottle of wine. Waiter opens bottle and pours small amount in glass. No, don't like that,can you open a different one please. Waiter pours first bottle down sink. Repeat ad infinitum.
Despite the 'show' some people insist upon, wine is very rarely 'corked'.

And This ^

The DP also needs to add to the email his name, address and phone number and invite the chef to contact him for some specialised catering tuition which the chef all too obviously needs(!).

The man sounds an insufferable "look at me" and "wannabe" boor...

I always suspected that this is how most of the restaurants on Gordon Ramsay’s Kitchen Nightmares ended up there: you know the ones, where the owner / chef is insisting “our food is excellent, everyone loves the food, there’s nothing wrong with the food, we ask all our customers how they’re enjoying their meals and nobody ever has anything but praise, our customers would tell us if they didn’t like the food…”

Turns out, customers don’t, they just say everything’s fine.

No if it’s substandard then that’s an issue to be mentioned.

i mean if it’s good or fine then you don’t give feedback

Yes, but that’s different! You were at a shit ‘throw it in the microwave’ place, and it wasn’t even barely adequate. It wasn’t edible! Of course you send it back. That’s different to the OP’s husband giving his five-minute rundown on why the carrots with sumac weren’t correctly spiced.

If there is really something to complain about, you do it very shortly after being served, so they have a chance to rectify it

If you eat the lot but then make a comment after you've finished, that's tedious and a bit of a dick move

Detailed feedback is better on Tripadvisor etc where management can take note

Definitely explain that it really spoils the occasion for you and you need him to rein it in

So in other words you think people should lie about a substandard meal unless there's a major problem? Blimey.

This ^

Oh, it's super cringy.

My sisters DH used to be/is the same. But if it was a female waitress, he'd also take the opportunity to attempt to flirt! Flirting and complaining about the food, with his literal wife - my sister - also sat there, was just dire beyond belief.

Worse still, he's got the cooking skills of a pre-school child. All I've EVER known him make is a spaghetti bolognaise, which, having sampled myself, is only average. So he's hardly in a place to criticize!

Yeah this is true I lived in the Netherlands so appreciate directness. I went out with a friend for lunch their roulade (starter)was frozen in the middle and my main was a bit vile. They waiter turned up and they said it was lovely. As they were paying I politely lied too. I wouldn’t go back though.

No he's never sent the food back. But is it any better storing up the criticism for the end?

Well it sounds like he doesn't want to send it back because it's only a small thing he comments on? He's only storing it up for the end because that's when they ask.

I'm guilty of just saying "yes, food was great thanks" when it wasn't. But I don't think he's doing anything wrong by politely answering the question asked.

I think I would do two things

1. pre warn the waiter that your DH might be a prick
2. just get up and go to the loo when the waiter asks.

or just jump in and say ‘oh mine was lovely!’

Definitely. As the only non-Brit in my circle of friends I find it laughable that the entire table will be complaining about their meal but when the waiter comes around everyone says "the meal is great" in unison. Why? Whom does it benefit? You? No, because you eat and pay for sub-par meal. Restaurant? Also no, because without feedback they have no way to improve. The whole "voting with your feet" which is so ubiquitous in Britain is just not a thing in most other countries. You don't like something, you say so and, ore often than not, it will be actioned.

This would annoy me unless there really is a genuine problem with the food being not up to the standard of the price. But that regularly, I understand why it’s embarrassing!
maybe talk to him about it again, reiterating how much it annoys you, and ask that in future unless something really isn’t right, he sticks with trip advisor reviews.

Your thread title doesn't quite match what is happening imo. He's not complaining in the sense that he's flagging the waiter down to tell them there's an issue, or sending the food back. He's just answering the question that's been asked.

Oops. I hope he checked for spit or worse in anything that was served afterwards.

I give up. 😂

Thing is, OP has told him it bothers her (and if it’s a case of the food not matching his personal taste then why does he need to complain?!) but he’s still doing it. It’s embarrassing for her.
Like a PP said, a server asking if everything is ok isn’t looking for a critique on the flavours etc, they’re asking if there is anything wrong (food is cold or something was missing etc). The chef can’t be expected to do something like make several different kinds of gravy for one dish!

When someone moans especially about something relatively minor, it really detracts from a night out for me. Maybe he’s doing it to show off his knowledge and to get one up on the chef - if so then he’s a bit pathetic.

Prat that waitstaff doesn’t know what’s serving? Isn’t that waitstaff job? Is there cheese in the XYZ? It’s the job.

Or prat for pantomiming if there’s a language barrier?

I think there's absolutely something to be said if there's something wrong with the dish. And maybe if its REALLY obvious, balance of flavours, over salted etc. But the fact he does it nearly 2/3rds of the time you go out smacks of performative foody-ism. Or not understanding that he's picky. Or not picking the right Michelin star restaurants for his preferences.

Maybe read the post I quoted again.

DH would sooner suffer in silence when given fries instead of potatoes or his sushi is a stodgy lump and I just don’t understand it. He also gets annoyed when I complain about incorrect orders I said that would annoy me. How you got from that I accept bad service meekly, I'm not sure.

But rest assured, I don't.