Paddington's Perfect Steak Dinner

Meanwhile, slice the onion into half rings and prepare the stock. Melt a knob of butter in a large frying pan over medium-high heat. When the pan is nice and hot, fry the steak with half of the onion for 1 - 3 minutes per side (see Tip). Reduce the heat to medium-low, then remove the steak from the pan and allow to rest under aluminium foil.

Tip: fry the steak for more or less time as preferred, depending on how rare you'd like it.

Deglaze the onions with the white wine vinegar and cook for 1 minute, then add the stock and half of the cream. Mix well and allow to simmer for 2 - 3 minutes, seasoning to taste with salt and pepper. Meanwhile, crush or mince the garlic. Discard the rosemary stalks and finely chop the leaves. 

Heat a drizzle of olive oil in a deep frying pan over medium-high heat and fry the garlic, remaining onion and rosemary for 1 minute. Add the spinach and the rest of the cream, mix well and fry for 1 - 2 minutes or until the spinach has wilted and reduced. Season to taste with salt and pepper, then reduce the heat to low and cover with the lid. Allow to simmer gently until serving.

Mash the potatoes with a knob of butter and a splash of milk or the reserved cooking liquid as preferred. Stir in the mustard and season to taste with salt and pepper.