Soak the cashews in the 1 cup of hot vegetable broth for 20 minutes, then blend the cashews and broth together for 2 minutes until thick and creamy. Set aside.
Heat 2 tablespoons olive oil in a large skillet over high heat and sear the mushrooms in a single layer without stirring for 3 minutes. Toss and cook 4 minutes more until deeply browned, then move them to a plate.
Lower the heat to medium, add the remaining tablespoon of olive oil, and cook the sliced onion for 7 minutes until soft and caramelized at the edges. Stir in the garlic for 1 minute.
Add the dairy free butter, sprinkle in the flour and tomato paste, and stir for 2 minutes until the mixture is glossy and rust colored.
Pour in the white wine and scrape the pan clean, letting it bubble away for 2 minutes. Add the 2 cups broth, dijon, soy sauce, smoked paprika, thyme, salt, and pepper, then simmer for 6 minutes until thickened.
Meanwhile, cook the noodles in salted water until al dente and drain.
Return the mushrooms to the skillet, stir in the blended cashew cream, and warm over low heat for 3 minutes without boiling. Finish with lemon juice and taste for salt.
Fold the hot noodles into the sauce or spoon the stroganoff over them, then shower with fresh dill and serve.