Prise open the scallop shells, pat the scallops dry with kitchen paper and leave in the fridge, uncovered, for 2-3 hours to dehydrate slightly.
Meanwhile, for the coriander salt, dry fry the coriander seeds and cinnamon stick in a frying pan over a medium heat for 30-40 seconds, or until toasted and fragrant.
Transfer the toasted seeds to a spice grinder and blend to a coarse powder. Tip the powder into a bowl and mix in the sea salt. Set the coriander salt mixture aside.
When the scallops have dried out in the fridge, preheat the grill to its highest setting. Remove the scallops from their shells and cut each in half to create two thinner scallops. Mix 160g/5½oz of the butter with the Marmite until smooth and well combined and set aside.
Heat a frying pan over a medium heat, add the diced chorizo and fry for 4-5 minutes, or until golden-brown.
Crack the eggs into the pan over the chorizo pieces and fry for 1-2 minutes, or until cooked to your liking. Remove the pan from the heat
Meanwhile, heat a separate frying pan over a medium heat until hot. Add the sunflower oil and the remaining 15g/½oz of butter. When the butter has melted, add the scallops and cook for 15-20 seconds on the cut side, or until golden-brown.
Remove the scallops from the pan and place them, cut-sides down, into a cold, ovenproof frying pan. Place the pan under the grill and grill the scallops for 30 seconds, or until just cooked through.
To serve, toast the bread until crisp and golden-brown. Place one slice into each of four serving plates. Season the chorizo eggs with a little of the coriander salt and freshly ground black pepper. Place one on top of each slice of toast and garnish with the coriander cress. Squeeze the lemon juice over the scallops, season with a little more of the coriander salt, then brush them with the Marmite butter. Place one scallop on top of each portion of chorizo eggs.