Cut ribs to smaller pieces (with about three to four ribs per piece)
Rub ribs all over with the mustard mix. Allow to marinate for 30 minutes at least.
In a large pan, heat a little oil over a high heat.
Sear ribs in batches until browned.
Put browned ribs on an oven tray. Cover with baking paper, then aluminium foil.
Bake in the centre of oven for about 2 hours.
In the ribs pan, add a splash more oil and fry the onion and garlic.
Add the butter and fry in, then add remaining ingredients and stir well.
Allow to cook over a medium heat for about five minutes, then strain carefully through sieve.
Return to the pan and reduce for a further five minutes until thick and syrupy.
Turn oven up to 220°c
After initial cooking time, carefully uncover to avoid steam, and transfer to a chopping board. (allow to cool for a few minutes so you can handle them) Cut the ribs into single ribs, return to oven tray and coat with the sauce, cook for 10 more minutes or so in the hot oven.
Firstly, prepare the pumpkin and cauliflower mash for the topping; In slightly salted cold water, add the diced pumpkin. Bring to the boil, simmer for a few minutes then add the Cauliflower whole garlic cloves. Bring back to the boil, lower temperature and simmer until both pumpkin and cauliflower are cooked.
Drain the cauliflower and pumpkin. (leave to sit and drain for about 10 minutes to ensure as much water has drained as possible)
Return the drained pumpkin and cauliflower to the pot and mash in 50g diced butter, the Oak smoked Paprika, a pinch or two of salt and a pinch of pepper.
Once mashed well, stir in the chopped thyme and a whole egg. Mix well and leave to cool.
To make the filling we need to make a basic white sauce (béchamel)
Melt 100g of butter over a medium heat in a sauce pan. Once melted stir in the plain flour. Using a whisk, stir over the heat continuously for a minute to allow the roux mix to heat and the starches to be released from the flour. Slowly pour in the milk whilst whisking gently to ensure and lump free white sauce.
Once all the milk has been poured in, gently heat the sauce, stirring continuously until it thickens nicely. Remove from heat.
Now, for the pie. Into the white sauce stir in the spring onions, diced fish, peas, sweetcorn, mushrooms and bay leaf.
Pour the white sauce and fish mixture into an oven proof lasagne dish. Allow to cool.
Top the fish mixture with the pumpkin and cauliflower mash and sprinkle with the grated cheese, a little more Oak Smoked Paprika and some more chopped thyme.
Bake in a pre-heated oven at 180 degrees centigrade for 40 minutes.