Prepare green salsa by placing tomatillos, onion, jalapeño, cilantro, and salt in a blender or food processor. Blend until smooth. Transfer to saucepan and cook until tomatillo sauce changes color to olive green, about 5 to 6 minutes.
Heat 1 tablespoon canola oil in medium non-stick skillet over medium high heat. Add potatoes and red bell peppers, stirring constantly until potatoes are lightly browned and peppers are tender, about 4 to 5 minutes. Season with salt and pepper, and set aside.
Warm tortillas for 10 to 15 seconds on each side in an ungreased pan.
Assemble flautas by spreading the mixture and shredded cheese evenly on center each tortilla, leaving a half inch border around the edges. Roll up the tortillas tightly. Heat 2 tablespoons canola oil on same skillet over medium high heat. Place flautas seam side down and allow to cook for 2 minutes. Carefully flip and continue cooking until evenly golden and crisp, about 4 to 5 minutes total.
Top flautas with warm green salsa and garnish with sour cream.