Short Rib Lasagna

Method

1. Tie the thyme, rosemary and parsley sprigs and the bay leaf in cheesecloth to make a bouquet garni, trim the excess cheesecloth and set it aside.
2. Place the dried porcini in a heatproof bowl, add 1 cup boiling water, cover and let stand until the mushrooms soften, about 20 minutes.
3. Lift the mushrooms out with a slotted spoon, chop them and reserve the soaking liquid.
4. Preheat the oven to 160°C.
5. Sprinkle the short ribs with salt and pepper.
6. Put the flour in a medium bowl, dredge the ribs in it, shaking off the excess, and place them on a rimmed baking sheet; reserve the flour.
7. Heat 2 tablespoons of the olive oil in a heavy large skillet over medium-high heat and brown the ribs in batches on all sides, about 6 minutes per batch, then return them to the baking sheet.
8. Heat the remaining 2 tablespoons olive oil in a heavy large pot over medium heat, add the carrots, celery and onion and cook, stirring often, until softened, about 10 minutes.
9. Stir in the chopped mushrooms.
10. Sprinkle 1 tablespoon of the reserved flour over the vegetables and discard the rest of the flour.
11. Add the tomato paste and stir until it begins to brown on the bottom of the pot, about 1 minute.
12. Add the Port and stir until almost all the liquid is absorbed, scraping up the browned bits, about 1 minute.
13. Add the red wine.
14. Pour in the reserved mushroom soaking liquid, leaving any sediment behind.
15. Bring to a boil and simmer, stirring often, until reduced by about one third, about 7 minutes.
16. Add the beef broth, garlic and bouquet garni and return to a boil.
17. Return the ribs to the pot, arranging them meat side down in a single layer, cover the pot and braise in the oven until very tender, about 2 1/4 to 2 1/2 hours.
18. Using tongs, transfer the ribs to a rimmed baking sheet to cool and discard the bouquet garni.
19. Shred the beef and discard the bones.
20. Spoon off the fat from the top of the sauce and discard it.
21. Boil the sauce until reduced to 5 1/2 cups, about 8 minutes.
22. Return the meat to the sauce, season with salt and pepper and stir in the chopped thyme.
23. Melt the butter in a heavy large saucepan over medium heat, add the flour and whisk until smooth.
24. Cook, whisking frequently, until light golden brown, about 6 minutes.
25. Add the milk, bring to a boil, whisking constantly, and boil for 1 minute.
26. Add the nutmeg and season the béchamel with salt and pepper.
27. Preheat the oven to 190°C and butter a 15x10x2-inch baking dish.
28. Spoon 1 cup of the meat sauce over the bottom of the dish, spread it in a thin layer and sprinkle 2 tablespoons of the Parmesan over.
29. Arrange 6 lasagna noodles over the sauce to cover it (the noodles may overlap slightly).
30. Drizzle 1 cup of the béchamel over the noodles, spread it in an even layer and sprinkle 1/4 cup of the cheese over.
31. Spread 2 cups of the meat sauce over the cheese.
32. Repeat the layers with the noodles, béchamel, cheese and meat sauce.
33. Cover with the remaining 6 noodles, spread the remaining béchamel over them and sprinkle the remaining cheese on top.
34. Bake the lasagna uncovered until the edges are bubbling and the top is golden brown in spots, about 45 minutes.
35. Let it rest for 10 minutes before serving.