First, take your lamb rump steaks out of the fridge and bring to room temperature while you get on with the red wine jus and celeriac.
to make the red wine jus
Heat the olive oil in a saute pan over medium-low heat. Saute the shallots and garlic for 10 minutes.
Measure in the port and wine. Add the fresh rosemary and bay leaves and simmer until reduced by half.
Add the lamb stock and simmer until reduced by half again.
Strain out the vegetables and herbs, reserving the liquid.
Return the jus to a clean pan and bring to a simmer. Stir in the butter and add a pinch of sugar. Season to taste.
for the celeriac puree
Peel the celeriac and cut into 1 cm small pieces.
Heat the butter in a small pan and saute the celeriac for five minutes, with the lid on.
Add the milk and season with salt and pepper. Cook for 10 minutes over medium heat with the lid on.
Transfer the cooked celeriac to a food processor or blender, leaving any excess liquid in the pot.
Blend until pureed, adding a little cayenne and enough double cream to reach the desired consistency. Stir in lemon juice.
Push the celeriac puree through a fine mesh sieve to remove any remaining lumps. Transfer to a clean bowl and refrigerate, covered, until needed.
to cook the lamb rump steaks
Drizzle the olive oil over the lamb rump steaks and season with salt and pepper.
Preheat your griddle pan to high and cook the steaks on each side for 3 minutes for medium-rare or 4 minutes for well-done. Leave to rest while you plate up the rest of the dish.
Notes
Both the red wine jus and celeriac puree can be prepared in advance and reheated when needed.