Put the potatoes in a medium pan of boiling water and cook for 15-20 minutes until tender, adding the peas for the final 2 minutes. Drain and roughly mash the potatoes and peas together. Preheat the oven to 180°C/Fan 160°C/Gas 4.
Combine the potato and pea mash, 1 egg, the herbs and flour in a large bowl and season to taste. Form the mixture into 8 patties. Mist a large non-stick frying pan with cooking spray, add 4 of the patties and cook for 2 minutes each side.
Transfer to a baking tray and keep warm, then repeat to make 4 more fritters.
Bring a deep pan of water to a boil and add the white wine vinegar. Break 1 egg into a ramekin. Swirl the water with a spoon to create a whirlpool and slide in the egg.
Cook for 2-3 minutes, then using a slotted spoon, transfer to a plate lined with kitchen paper. Repeat with the remaining 3 eggs.
Serve 2 fritters per person, and top with a poached egg. Season to taste and serve with the salad on the side. The uncooked patties can be frozen in an airtight container for up to 3 months.