Mr Herewini said it was "crazy how popular those mushrooms were".
"Those mushrooms and a loaf of bread and that was your dinner. Now that all us children are adults we have acquired the taste but as kids we couldn't understand why everyone loved them so much.
"I remember working at the diner and we would go through 20kg on Thursday, Friday and Saturday nights. Then if we ran out, we would almost have a riot on our hands," Mr Herewini said with a laugh.
"I would be at school and teachers would come up to me asking for the recipe. Even now living in Perth I will bump into people from Rotorua who ask me about those mushrooms.
"The funny thing is, it is the most simple recipe, when we tell people, nobody believes us, convinced there is cream and all sorts in it. But at the same time, nobody seems to be able to pull them off."
Mr Herewini said the family was talking about having a "mushroom off" to see who could make the best batch.
"I only ever learnt how to do them in 10kg batches because that's what we would do at the diner. When I try to reduce it doesn't come out the same. My wife thinks she makes the best mushrooms but I think my mother would have to win being the mushroom queen."
Mr Horvath was farewelled in Rotorua today.
Recipe: Joe's Diner Mushrooms
10kg mushrooms, washed
3 pounds (1.3kg) butter
Flour
750ml soy sauce
Method:
Put 1 pound (450g) butter in a big pot and mix with the 10kg of mushrooms on a high heat, allowing the mushrooms to boil down.
Once all mushrooms have been added, leave to boil for four or five hours, drawing out the flavour in the mushrooms.
Add 750ml of soy sauce to the pot and mix about.
In another pot, melt 2 pounds (900g) butter, mixing in flour to make a creamy paste.
Add the paste to the pot of mushrooms and mix until it thickens.
We asked our Facebook readers what their favourite item on Joe's Diner menu was:
- "Can't get enough of them mushrooms."
- "Mushrooms mushrooms mushrooms ... at 2am when you can't walk."
- "Steak and mushroom toasted sandwich and his good old hamburger, rest easy Joe."
- "Mushrooms, for sure, RIP and deepest condolences to Joe's whanau."
- "Best cheeseburger and mushrooms. RIP Joe, kia kaha whanau."
- "Me and my husband always called in there after a mean night on the town. Ordered steak meal with 4 buttered bread and the pot of mushrooms for myself! Loved it, thank you for your kindness and happiness you shared to all the people involved in your mean takeaway shop."
- "Moe mai ra cooky. I'll never forget your mushroom sauce and hot chips."
- "Mushrooms and hot chips after night clubs, they were the best."
- "Sorry to hear Joe has passed away. Loved his burgers and visiting Joe's Diner - he was a legend!"
- "Mean feeds after clubbing, miss the mushrooms."
- "Definitely steak, eggs, chips and his yummy mushrooms ... R.I.P Joe."
- "Steak and cheese burger! Never had one like it since."
- "Double egg burger (runny egg) chips and pot of mushrooms ... Regular order of mine and they would start cooking as soon as they saw me (back in the 80s). Then Uncle Joe would peep through the door and ask 'so where have you come from and who is that with you?' With a grin on his face. What a beautiful man he was and yes a legend ... You were sadly missed when the diner closed and now that you have passed, the emotions will be running high again. R.I.P Uncle Joe."
