Bring large pot of water to a boil. Add pasta and cook to al dente. Add peas to the pot right before finished cooking. Drain immediately and set aside.

In a large saucepan, heat olive oil over medium heat. Add onion and sauté until it starts to soften. Add potato, garlic, salt, and red pepper flakes and continue to cook for another 5 minutes, until potato is soft.

Add cashews and water and simmer for 5 minutes. Transfer mixture to blender and add nutritional yeast and vinegar. Blend until smooth.

Pour cashew mixture into pot with pasta and peas. Return pot to medium heat, stirring gently, until pasta is warm. Serve immediately.