In a medium skillet over moderate heat melt 2 tablespoons butter, add parsley and sliced beets. Warm through, season with salt and serve.
In a second skillet, also over moderate heat, melt remaining butter, add onions and warm through. Add peas and cook 5 minutes. Season with salt and transfer to a serving dish.
If your stovetop is too crowded when you find your pocket-of-time to deal with the sides, feel free to use your microwave for either of these dishes, loosely covering beets or peas. Microwave on high, but check them every couple of minutes -- you're just warming them through and melting the butter.