Put a medium pan of salted water on to boil. Put the spinach in a large frying pan. Set over a medium heat and cook, stirring, for 3-4 mins till it wilts.
Tip the spinach into a colander and press down with the back of the spoon to squeeze out as much water as possible. Set aside to carry on draining in the colander.
Scrub the new potatoes and chop them into equal-sized chunks, around 2cm across. When the water is boiling, add the potatoes. Simmer, lid on, for 10-15 mins till the potatoes are just tender when you press a skewer into them.
While the potatoes cook, peel and finely slice the red onion. Peel and crush or grate the garlic. Halve the chilli and flick out the seeds and white bits for less heat. Finely chop it. Drain and rinse the borlotti beans.
Wipe the spinach pan with kitchen paper and set it over a medium heat for 2 mins. Add 2 tsp olive oil and the onion. Season with salt and pepper. Cook for 3 mins till a little browned. While the onion cooks, roughly chop the spinach.
Drain the potatoes. Add the potatoes to the pan. Season with another little pinch of salt and pepper and put on a lid. Cook for 10 mins, stirring now and then, till the potatoes have picked up a little colour. (If your pan doesn't have a lid, lay a baking tray over the top to trap in the heat.)
Stir the garlic, chilli and 1 tsp sumach into the potatoes. Add the spinach and borlotti beans. Cook and stir for 2 mins to warm everything up.
Crack the duck eggs into the pan. Put the lid back on and cook for 4-5 mins to just set the eggs (or cook for a few mins longer for fully set egg yolks). Scoop the pan fry onto 2 warm plates. Dust with ½ tsp sumach each and serve.