Unsurprisingly, the inspiration for their giant burger came a few years ago from the home of everything super-sized, the United States.
"We got an email from someone about an American place where they had this massive burger ... so we thought we should try and make that burger ourselves."
They then hit the first hurdle - where to get buns big enough. Their local bakery solved the problem, fashioning a prototype about three times as wide as even the largest available at most takeaway shops.
Measuring 19cm across, the bun itself is enough to scare off many customers who ask the Jouberts exactly what they mean by Jumbo.
What goes in between reads like a typical family grocery shopping list - half a lettuce, a whole chopped tomato, three fried eggs, two large slices of shoulder bacon, three or four gherkins, a quarter of an onion, mustard, tomato sauce and a special cheese sauce that flows down the sides of the beast.
The burgers are two 180g patties that, as hefty as they are, are placed alongside each other rather than stacked. One of its patties constitutes 30.6g of fat - nearly 5g more than that of an entire Big Mac.
Carl Nelson holds the honour of being the first person to eat the entire stack. He was a teenager working at the store at the time and accepted a challenge that he wouldn't be charged if he could finish the heap in one sitting.
Over the busy summer season, the shop sells about 10 of the $20 burgers each week, and Mrs Joubert guessed only about every one in two customers could finish one.
"It's not a big seller, just mainly a fun thing, and it's all mainly big guys who order it," she said.
The record for the biggest burger commercially available goes to Juicy's Outlaw Grill in Corvallis, Oregon, for a burger weighing 352.44kg, which costs $6000 and demands 48 hours notice to prepare.
The day I met my mountain
If the Jumbo Burger was to be my Everest, I was to be its George Mallory.
But unlike the great mountaineer, at least I could walk away - albeit sluggishly - from my failed attempt.
I'd agreed to the challenge with the giddy bravado of a youngster sailing off to war with romance and adventure in his heart, the horrific reality yet to come.
That probably hit home when the beast was set down before me.
Gluttony being my favourite sin, I plunged into a headlong frontal assault and soon found myself painfully bloated and building a pile of messy napkins.
The "meat sweats", which I had assumed were a myth, came on after just three minutes of gnawing at the flanks of the monster.
In the end it became a question of basic geometry. More than a kilogram of hamburger could not fit in my already swollen stomach.
So with fallen pride but mobility intact, I abandoned my pursuit with a quarter of the Jumbo still on the plate.
Just as it did for Mallory in 1924, victory had come within cruelly short reach - but even one more bite was too far.
The bastard had knocked me off.
By the numbers
McDonald's Big Mac
Price: $5.60
Weight: 195g
Fat: 25.9g
Saturated Fat: 4.8g
Burger King Whopper
Price: $6.80
Weight: 298g
Fat: 36.8g
Saturated Fat: 11.3g
Angelo's Pizzas Jumbo Beef Burger
Price: $19.95
Weight: 1.5kg
Fat in one meat pattie: 30.6g
Saturated fat in one meat pattie: 15.3g
Probable fat: Well over 100g
