Salads need not focus on the lettuce. Here the greens take a back seat to vibrant golden beets. The salty, creamy blue cheese and the crunchy walnuts complement the sweet beets. Roasting the beets in water prevents them from drying out.
Place the beets in a roasting pan and add water to a depth of 1/2 inch. Cover the pan with foil and bake until the beets are easily pierced with a fork, about 1 1/2 hours. Set the beets aside until they are cool enough to handle. Peel and rinse off any pieces of skin. Slice the beets into 1/2-inch-thick rounds, and then cut them into 1/4-inch-thick sticks. Let the beets cool to room temperature.
Toss the beets with the rice vinegar, salt, and pepper. Add the olive oil and mustard and toss with the spinach. Garnish with the toasted walnuts and crumbled blue cheese.
Make Ahead: You can roast the beets up to 3 days in advance; toss them just before serving.
