For the cheese: In a medium pot, combine the milk, buttermilk and lemon juice in a medium pot and bring to 112 degrees F over low heat. Cook without simmering until the liquid separates into solid curds and whey, 45 to 50 minutes. Remove from the heat.
Using a slotted spoon, transfer the solids to a fine mesh strainer or colander lined with cheesecloth. Bring up the 4 corners of the cheesecloth and tie them together. Gently twist to extract as much liquid as possible. Place over a bowl and let drain in the refrigerator until thick and the liquid has drained away, about 30 minutes. Twist again to extract as much water as possible. Remove the cheese from the cheesecloth, wrap, and place in a bowl. Add the sage and season with salt and white pepper, mixing to combine.
For the salad: Place the beets in a saucepan and cover with water by 1-inch. Bring to a boil, lower the heat, and simmer until tender, 15 to 20 minutes. Drain and shock the beets in ice water. Remove the skins and stem ends. Julienne and reserve for the salad.
For the vinaigrette: In a bowl, whisk together the mustard and lemon juice. Slowly add the oil, whisking until emulsified. Whisk in the shallots, rosemary, and sage, and season with salt and freshly ground black pepper.
In a large bowl, toss the beets, endive, fennel, pear and walnuts with the vinaigrette to lightly coat. Adjust the seasoning, to taste, with salt and freshly ground black pepper.
Divide the salads among 4 plates and top each serving with 1/4 cup of the ricotta, sprinkling it on and around the salad.
Yield: 4 servings