Preheat oven to 200°C/400°F. Add the mixed mushrooms to a parchment-lined baking tray. Move to the oven and roast until reduced significantly in size and beginning to brown in places, about 20-30 minutes.
Meanwhile, add the porcini mushrooms to a heatproof bowl or measuring jug. Pour over the boiling water, cover and allow to soak for at least 20 minutes. Once tender & rehydrated, remove from the liquid (keep the liquid) and roughly chop them.
While the mushrooms are soaking and roasting, add the lentils to a small saucepan and cover with cool water. Cover the pan and set over high heat. Bring to a boil, reduce the heat to medium-low, and simmer until tender - about 15 minutes. Drain and set aside.
In a large saucepan or Dutch oven, add the olive oil and set over medium-high heat. Once shimmering, add the carrot, celery and shallot along with a generous pinch of salt. Cook, stirring occasionally, until the vegetables begin to brown - about 7-10 minutes.
Add the garlic, chili flakes, thyme and tomato paste. Cook for another 2-3 minutes, just until very fragrant and the tomato paste takes on a darker colour. Sprinkle over the flour and cook for 1-2 minutes longer.
Pour over the wine and cook until it's reduced significantly, the strong alcoholic smell has cooked off and there is a jammy consistency - about 2 minutes.
Stir in the tomatoes, soy sauce, roasted mushrooms, porcini mushrooms, cooked lentils and the mushroom soaking liquid. Bring to a simmer and allow to simmer for 10 minutes. Taste to adjust for seasoning, adding more salt and pepper if needed. Serve.