Tender sweet potatoes and sauteed savory kale balance one another in this quick, weeknight-friendly frittata. Smarts: If making frittatas for more or less than 4 people, try making them in muffin tins (recipe makes 2 muffin-size frittatas per person). Mini frittatas freeze well too!
Heat 9” to 10” (22.5 to 25cm) skillet over medium heat (skillet size is based on 4 servings - you may need a smaller or larger skillet if you're customizing). Add cooking oil and then onions to heated oil. Saute until softened, ~3 minutes. Add kale and saute until tender, ~2 minutes more. Add sweet potatoes and stir gently to combine. Season lightly with salt and pepper.
Pour the egg mixture over the veggies. Stir until all ingredients are evenly distributed. Transfer to the oven and bake for 20 to 25 minutes, until a knife comes out clean.
While frittata is baking whisk together shallots, both vinegars, honey, mayonnaise and oil. Season with salt and pepper. Toss vinaigrette with lettuce, bell peppers and pepitas.
Serve frittata warm out of the oven topped with a dollop of sour cream and with salad on the side.