For the oxtail, season the pieces of oxtail with salt and freshly ground black pepper and lightly dust them with a little flour.
Place the oxtail into a roasting tin and roast in the oven for 30 minutes, turning the oxtail pieces after 15 minutes to make sure they are nicely coloured on both sides.
Meanwhile melt the butter in a pan over a low heat and gently cook the onion, garlic and thyme for 3-4 minutes until soft, stirring occasionally.
Add the flour and the tomato purée and stir well.
Gradually pour in the red wine and stock, stirring well between additions to avoid lumps forming, then bring the mixture to the boil.
Add the pieces of roasted oxtail to the pan, then cover and simmer gently over a low heat for about two hours. Check the pieces of oxtail - the meat should be tender and easily removed from the bone. If not, replace the lid and cook for another 15 minutes and test again.
Drain the oxtail into a colander over a bowl to reserve the sauce.
When the oxtail is cool enough to handle, remove the pieces of meat from the bone and place into a clean saucepan and cover with the reserved sauce. Bring to the boil, then reduce the heat and simmer until the sauce has reduced enough to just coat the meat.
Meanwhile, for the dressing, whisk all of the dressing ingredients together in a clean bowl and season, to taste, with salt and freshly ground black pepper.
For the salad, place the pea shoots, salad and herb leaves, peas and broad beans into a bowl and cover with most of the dressing. Mix well to coat and arrange a little salad in the centre of each serving plate.
To serve, spoon a little of the warm oxtail meat around the salad with a small amount of sauce just coating the meat, then spoon a little of the remaining dressing over the oxtail.