First, heat your oven to 150C and then place a large casserole on the hob over a medium heat and add a splash of oil. Add the shallot and celery and cover, so that they sweat, rather than caramelise.
Whilst the vegetables are gently cooking, dust the oxtail pieces with plain flour, seasoned with salt and pepper. Place a frying pan on the hob, over a medium to high heat and add another splash of oil. Place the pieces into pan and brown all over, working in batches, so that everything does become too crammed. Put the oxtail on a warm plate once done.
By now, the vegetables should be nicely soft and slightly coloured so add two thirds of the chopped garlic and the bouquet garni and turn the heat up a touch. Stir for a minute so that the garlic softens but doesn’t catch and so that the herbs can begin to release their oils and then shake the casserole to distribute evenly.
Pop the oxtail pieces on top of the vegetables and pour in the dashi stock, the red wine and add the tomato puree. Bring to a gentle simmer, cover and then place the casserole into the oven, for 2 and half to 3 hours. Or until the meat is soft and tender.
Meanwhile, bring a saucepan of salted water to the boil and blanch the baby carrots for 5 minutes and refresh in a bowl of iced water.
Repeat again with the asparagus but this time only blanch for 2 minutes and refresh in a bowl of iced water.
When the oxtail is ready, remove from the cooking liquor and keep warm. Strain the sauce through a sieve into a saucepan and remove the shallot and celery pieces and keep warm with the oxtail.
Place the saucepan back on the hob, reduce the sauce by two thirds.
Whilst the sauce is thickening, place a griddle pan on the hob over a high heat and put the carrots on with a drizzle of oil. The aim is finish the carrots off and warm through and add some chargrilled flavour and stripes. Once done, slice each carrot in half and keep warm. Repeat the same process with the asparagus
As the carrots and asparagus are grilling, now is the time to mix together your ingredients for the gremolata. So, throw the remaining garlic, parsley and lemon zest into a small bowl and mix together.
To plate up, arrange the oxtail into the centre of a bowl, large and small pieces and place a few of the shallots and celery around the side.
To finish the sauce, quickly whisk in the butter for a bit of sheen and add some of that lemon juice.
Pour the sauce over the oxtail and arrange the chargrilled veg to the side.
Finish by scattering over some of the gremolata over the top and serve with some bread to mop up.