Slice the aubergine into thin, wide strips and griddle on a hot pan. Remove and set aside.
In a large frying pan, add the butter. Once melted, add the red onion and garlic and cook for 5 minutes or until soft. Add the cumin seeds and continue to cook for a further 1 minutes.
Stir in the spinach leaves and continue to cook for a further 1 minute or until all the leaves have wilted. Season with salt and pepper and set aside.
To make the poach eggs, fill a medium sized pan with water and add a splash of white wine vinegar. Bring the water to a simmer and turn down as low as you can. Make a swirl with the water using the end of a wooden spoon and break the egg into the middle of the pan. The egg should come together in the swirl. Cook for 3-4 minutes and remove with a slotted spoon and set aside.
To make the hollandaise sauce, half fill a medium-sized pan with water and bring to a simmer. Put a glass bowl on top that fits snuggly into the pan without touching the water. Turn the heat down to as low as you can.
Melt the butter in a separate pan and when melted remove from the heat.
Place the egg yolks into the bowl over the heating glass bowl and begin to whisk continuously. Add the vinegar and lemon juice and continue to whisk until the mixture thickens.
Slowly pour in the melted butter and continue to whisk until the sauce is smooth and thick.
Remove from the heat and keep warm. Keeping it in a thermos flask is a good way to do so if you are not using it immediately.
To serve, toast 4 slices of sourdough bread and butter. Top each slice with some of the griddled aubergine and spinach mixture. Add a poached egg to each and drizzle with the hollandaise sauce. Sprinkle with chili flakes and proudly serve.