Peel the sweet potatoes. Chop into small cubes around 2 cm across. Heat 1 tbsp olive oil in a deep frying pan or wok. Add the potatoes and cook them, stirring often, for 5 mins.
While the potatoes cook, peel and thinly slice the onion. Halve the pepper and scoop out the seeds and white bits. Roughly chop the pepper. Add the onion and pepper to the pan. Cook and stir for 5-8 mins till the potatoes are tender.
Dice the chorizo. Add it to the pan. Fry for 3 mins till the red oil from the chorizo starts to run out into the pan.
Whilst the chorizo cooks, add the beans and their liquid to a small pan and place on a low heat. Peel and crush the garlic. Add it to the beans. Simmer gently for 2-3 mins to warm through.
Chop half the chervil leaves and stir them into the beans (see our tip below for what to do with the stalks). Pop a lid on the pan. Take it off the heat. Leave to one side.
Heat 2 tsp olive oil in a frying pan. Crack in the eggs. Cover. Keep the heat low. Fry for 2-5 mins till the yolks are as set as you like them.
Season the hash with a little black pepper. Spoon the hash onto warmed plates. Top with the beans, an egg each and scatter the rest of the chervil.