Tip the porcini into a heatproof bowl. Cover with 200 ml boiling water and set aside. Peel the shallots (keep them whole). Finely slice the leek and celery. Slice the carrots into 2 cm diagonal chunks.
Thickly slice the portobellos and any large mushrooms from the souping pack, leaving any smaller ones whole. Peel and thinly slice 2 of the garlic cloves.
Heat 2 tsp oil in a large pan over a medium heat. Add the whole shallots to the pan. Cook for 3 mins till browned. Add in the leek, celery and carrots. Season. Cook, stirring, for 3 mins.
Add in the mushrooms and garlic and fold through the veg. Cook for 5 mins. Pour in the porcini along with their soaking liquid. Let it bubble up.
Tip in the tin of chopped tomatoes. Add the thyme leaves and stir. Cover and simmer for 15 mins.
While the bourguignon is simmering, peel and grate or crush the remaining garlic clove. Finely chop the parsley stalks and leaves. Zest and juice the lemon. Whisk together in a small bowl with 1 tbsp water and 1 tbsp oil. Season. This is your gremolata.
After the bourguignon has cooked for 15 mins, taste and adjust the seasoning. Serve in warm bowls with the gremolata drizzled on top.