Mushroom Stroganoff over Fettuccine

I found this recipe in Neal Barnard's The Cancer Survivor's Guide.  Dr. Barnard's standards for diet are very similar to those of Drs. Caldwell Esselstyn, John McDougall, and Joel Fuhrman.

Ingredients
1 1/2 cups plus 2 tbs water
1 small onion, diced
1 pound cremini or button mushrooms, sliced
6 to 8 garlic cloves, minced
8 oz seitan, cut into strips
1 cup roasted red bell peppers, chopped
3 tbs unsalted tomato paste
2 tsp paprika
1/2 tsp ground black pepper
1/4 cup raw cashews
1 1/2 cups cooked or canned white beans, rinsed and drained
1/2 cup bean cooking liquid, water, or vegetable broth
2 tbs red wine vinegar or balsamic vinegar
2 tsp soy sauce (or Bragg Liquid Aminos)
12 oz fettuccine noodles (preferably whole grain)

Directions

1. Heat 1/2 cup of the water in a large nonstick skillet. Add the onion and cook and stir over high heat for about 5 minutes, until translucent.

2. Reduce the heat to medium. Stir in the mushrooms, garlic, and 2 more tablespoons of the water. Cover and cook for 5 minutes, stirring occasionally.

3. Add the seitan, bell peppers, tomato paste, paprika, and pepper.  Cover and cook over medium-low heat for 5 minutes.

4. Combine the cashews and the remaining cup of water in a blender. Process on high speed until completely smooth, about 2 minutes.  Add the beans and the bean cooking liquid and process on high for about 1 minute, until completely smooth. Pour into the skillet with the mushrooms.  Add the vinegar and soy sauce and stir until evenly mixed. Heat gently, adding additional water as needed, 1 tbs at a time, to achieve the desired consistency.

5. Cook the fettuccine in boiling water until just tender. Drain and rinse under cold water. Top with the mushroom mixture and serve immediately.

6. Stored in a covered container in a refrigerator, leftover Mushroom Stroganoff over Fettuccine will keep for up to 2 days.