William and Kate were in east London as part of an afternoon of engagements to highlight how communities have been coping during the coronavirus pandemic.
The couple handled dough with ease at the bakery, kneading it into balls big enough to make 30 4oz bagels.
Complemented on her technique, Kate laughed: "Just wait until you see the aftermath. I had beginner’s luck, they are getting worse."
Beigel Bake opened in 1974 and has thrived as a family business, opening 24 hours and churning out on average 3,000 bagels a day.
But they were forced to drastically reduce their opening hours as a result of the coronavirus crisis and most staff were put on furlough.
The owners refused to let it dampen their spirits, however, helping to deliver food to vulnerable members of the local community and taking part in a food donation programme, Feast.
Today business is still tough, having lost the tourists that would come to Brick Lane to try its delicacies, but most of the staff have been brought back.
"We are so excited to come to your famous shop,’" William told Amnon Cohen, 70, one of the co-founders, who started the business with his late brother, Asher.
The couple were slightly muffled through their masks but waved at the ladies behind the shop counter, Fiona McVeagh, 64, who has worked there for 33 years, and Dalia Urbanik, 43, who has been there for 16.
"How has the supply chain been?" asked William. He was told that had been fine although sanitation products had been hard to get hold of.
Eyeing up the goodies, William remarked: "This is a dangerous shop to be in!"
The couple were taken through by Amnon’s son, Elias Cohen, 27, to watch the bagels being made from scratch. They are boiled for around three minutes before being baked for 20 minutes at around 550F.
The couple were then handed aprons, hand sanitiser and gloves and tried their hand at kneeling the dough.
They laughed and giggled as they were told to knead and squeeze the dough but earned the approval of Amnon Cohen and his business partner, Sammy Minzley.
She said admiringly: "They are pretty good, especially [Kate]. She’d clearly knows how to bake."
Afterwards, a tearful Amnon said the royal visit was the "proudest moment of my life". Speaking later, Elias said it had been a tough time for the shop.
He said: "We have seen big changes, unfortunately. We had to reduce our hours. We initially remained open 24 hours but people weren’t coming to the shop.
"We had to furlough our staff. Fortunately we were later able to slowly expand our hours again and are now open 24 hours again. It’s steady, we are serving. But it’s not like it was before. It’s definitely quieter.
"Funnily enough people were upset when they found we weren’t open 24 hours because this place is such an institution.
"We have never lost our sense of family and community, though. And we never will."
Elias said the business had been helped by the fact that they had already started working on a home delivery app of their own - Beigel Bake - and getting the word out about their reopening on social media.
Later in the day, the Duke and Duchess visited the East London Mosque and London Muslim Centre to meet staff, volunteers and local business leaders who helped provide food parcels during the pandemic.
The mosque's senior Imam Mohamed Mahoud brought up the issue of mental health - championed by the couple through their Heads together campaign - when he spoke to the royals.
The Imam, who received an OBE from William last year for services to his community, said later: "I highlighted the issue of people increasingly needing support with their mental health - the Muslim community aswell as the rest of the UK who have been horrifically affected by the pandemic in terms of losing jobs and livelihoods."
He added that the visit by the royal couple had real importance for East London's Muslims: "It's an incredibly significant visit.
"The Muslim community often feel they have to do more than what is required to be recognised as part of mainstream society and their visit to the East London Mosque and Tower Hamlets borough helps us with that cause in establishing ourselves as part of the mainstream.
"It recognises our existence first of all and contributions we've made and the sacrifices and the pains and struggles of people, especially from the Bame (black, asian and minority ethnic) community.”