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.

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.

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

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 tablespoon at a time, to achieve the desired consistency.

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

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

PER SERVING: 403 calories; 4.5 g fat; 0.8 g saturated fat; 10% calories from fat; 0 mg cholesterol; 23.4 g protein; 68.9 g carbohydrate; 4.5 g sugar; 8.9 g fiber; 322 mg sodium; 90 mg calcium; 6.5 mg iron; 44.3 mg vitamin C; 789 mcg beta-carotene; 1.6 mg vitamin E