For the roast potatoes and spinach, preheat the oven to 190C/170C Fan/Gas 5. Bring a large saucepan of salted water to the boil. Add the potatoes and par-boil for 10 minutes. Drain the potatoes then place in a roasting tin. Drizzle with the oil, season with salt and roast in the oven for about 25–30 minutes, or until crisp and golden.
Transfer the potatoes to a large bowl and stir in the spinach. The spinach should wilt with the heat, but if not then transfer to a saucepan over a very low heat with the lid on and stir until wilted.
For the summer herb velouté, melt the butter in a heavy-based pan. Sweat the onion for about 10 minutes, or until it is translucent. Add the milk and cream and bring to the boil. Add the herbs and bring back to the boil. Remove from the heat.
Blend in a food processor until completely smooth. Pass through a fine sieve and season with salt to taste. Set aside (this sauce can be made ahead and stored in fridge for a day).
For the crispy eggs, bring a small saucepan of water to a rolling boil. Gently place 4 eggs into the boiling water. Cook for exactly 4 minutes. Remove from the water and immediately refresh in iced water. Peel the eggs.
Preheat a deep fat fryer. (CAUTION: hot oil can be dangerous. Do not leave unattended.) Whisk the remaining egg in a small bowl. Season the flour with salt and pepper. Place the whisked egg, flour and breadcrumbs in separate shallow dishes. Dip the cooked eggs in the flour, then the egg and then the breadcrumbs. Deep-fry for 2 minutes until golden brown. Cut each egg in half.
For the pan-fried cod, heat the oil in a frying pan. Fry the cod, skin-side down, for a few minutes, or until the skin is golden. Turn the fish over and fry on the other side, until cooked through. Season with salt and pepper.
Serve the cod with the herb sauce poured over the top, the potatoes and spinach on the side and the crispy egg halves on top. Garnish witht the flowers, if using.