“The great thing about burgers is that you can make loads ahead of time and freeze them, especially for the barbecue season,” says David Atherton, winner of 2019 Great British Bake Off.

These veggie burgers are served with brioche-style buns enriched with sweet potato instead of the usual butter, sugar and egg. Atherton adds: “It might be difficult to imagine until you’ve tried one, but the heavy, earthy sweet potato actually makes these rolls incredibly soft, fluffy and golden.”

David Atherton’s beet burgers and sweet tato buns

Ingredients:(makes 8 burgers and buns)

For the burgers:250g canned black beans, drained100g cooked beetroot, finely chopped80g prunes, finely chopped100g Cheddar, finely grated80g sweet potato, peeled and finely grated4 garlic cloves, finely grated150g sourdough breadcrumbs2tsp white miso2tsp Dijon mustard1tsp smoked paprika1 large egg2tsp fine salt10g fresh flat-leaf parsley, finely chopped40g quinoa8 Sweet tato buns (see below) or shop-bought burger buns

For the buns:260g sweet potatoes20ml light olive oil, plus extra for greasing1tsp salt2tsp instant yeast140ml warm water340g strong white bread flour60g strong wholemeal (whole-wheat) bread flour1 medium eggBlack sesame seeds, for sprinkling on top

Method (to make the burgers):

1. Preheat the oven to 180°C fan (200°C/400°F/gas mark 6).

2. Put the black beans onto a baking tray and bake for 15 minutes to dry them out. Add these to a mixing bowl, allow to cool slightly, then squeeze with your hands a few times until they are slightly mushed but you can still easily tell they are beans.

3. Add the beetroot and prunes to the mix, along with the cheese, sweet potato, garlic and breadcrumbs.

4. In a small bowl, whisk the miso, mustard, smoked paprika, egg and salt with a fork until smooth. Add this to the mixing bowl with the parsley, then mush the whole thing together until it is all combined. Shape the mix into eight burgers, each 1cm thick. Sprinkle the quinoa onto a plate and press the burgers into this on both sides to give a crunchy crust. Chill in the fridge for at least one hour or until ready to cook.

5. To cook, bake in the oven for 10 minutes, then fry for six minutes on each side in a frying pan on a medium heat, then one minute on each side on a high heat to get a good char. Alternatively, grill on a barbecue for six minutes on each side. Serve in the sweet tato buns (see method below) with your choice of condiments.

Method (to make the buns):

1. Preheat the oven to 180°C fan (200°C/400°F/gas mark 6).

2. Start by roasting the sweet potatoes in their skin for 40 minutes. Once cooled, peel and blend until smooth. This can be done ahead of time; I freeze this as portions so I can defrost when needed.

3. Mix the sweet potato pulp, oil, salt, yeast and warm water, then add the flours and bring together to form a dough (this is a sticky dough). Cover with beeswax wrap or clingfilm and leave to rest for 10 minutes.

4. Now you have to gently knead for five minutes. I prefer to do this in the bowl and just use a spatula. You are not really kneading so much as stretching the dough. If you have a stand mixer and a dough hook it is a lot easier. Cover and leave in a warm place to rise until doubled in size (about one hour).

5. Knock back the dough and divide into eight pieces. Form these into tight balls and transfer to a lined baking sheet (spaced well apart, about 5cm).

6. Cover with oiled clingfilm and leave until at least doubled in size (about one hour, but don’t worry if it’s longer, definitely make sure they’ve doubled in size). At this time, preheat the oven to 200°C fan (220°C/425°F/ gas mark 7).

7. Beat the egg, then gently brush the egg wash on the buns and sprinkle with the sesame seeds before baking for 12–14 minutes.

8. Allow to cool before slicing with a serrated knife. These are best eaten fresh, but are good the next day toasted.

Good To Eat by David Atherton, photography by Ant Duncan, is published by Hodder & Stoughton, priced £25.