Trim the beef cheeks so that all of the sinew has been removed. Cut it into two even sized pieces. Peel the onions and cut them into quarters. Peel the carrots and cut them into three pieces. Place the beef, vegetables and wine into a bowl and refrigerate for about 12 hours. If the wine does not cover the meat, turn half way through the marinating time. Drain the meat and vegetables through a sieve and keep the red wine to one side. Dry the meat and vegetables on a clean kitchen towel.
Heat the 50ml rapeseed oil in a small casserole until it is very hot. Season the beef with salt and pepper and then sear on all sides until reaches a dark golden colour all over.
Remove the beef from the pan and put to one side. Add the vegetables to the same pan and cook on a high heat until they start to caramelise. Once they start to catch, turn down the heat to low and cook with a lid for about 10 minutes stirring from time to time, this will soften the vegetables and develop their sugars.
Remove the vegetables from the pan and pour the wine straight in, scraping the base of the pan to remove any caramelised vegetables. Cook on a high heat until the wine has reduced by half. Add the meat, vegetables and beef stock back into the pan and cook on a high heat until the stock starts to simmer. Turn the heat right down so the stock is just below simmering point, you should be able to see the stock moving a little but without any sign of simmering. Cooking the meat at this temperature will help to keep the meat moist once it is cooked.
Cover the surface of the stock with some baking parchment and cover with a lid. Cook for about 4 hours or until a skewer slides into and out of the meat without any resistance. Remove from the heat and allow to cool slightly in the stock.
Place the vinegar, mustard, sugar, salt and egg yolk into a bowl and allow to come up to room temperature. Whisk the oil into this mix drop by drop until the mix starts to thicken and then in a thin stream until all the oil has been incorporated. Taste and adjust the seasoning.
Place the Jersey Royals in a pan of cold water, season with salt, add the tarragon and place on the heat and cook for 20min on a simmer. When cooked, drain, place back in the pan, add half the butter and lightly crush with a fork.
Peel the asparagus and trim the woody ends. Cook in boiling salted water for 3 minutes, remove and place in a pan with the other half of the butter.
Carefully remove the beef cheeks and place in a clean pan. Strain half the cooking liquid over the cheeks and start to heat up and reduce the sauce. Once it starts to thicken slightly, spoon over the meat to glaze.
To make the parsley crumbs, add the parsley garlic and bread in a hand blender and whiz to obtain green crumbs.
To serve, spoon the crushed Jersey Royals into a box, place a couple of spears of asparagus next to it, place a couple of beef cheeks on top, drizzle over the reduced sauce and finish with a spoon of mustard dressing and a sprinkle of parsley crumbs.