This recipe comes from my long-defunct blog, and I am pretty sure it was inspired by an article in Metropolitan Home, back in about 1992, or 3, or 4. It accompanied the story of a cute young couple so poor that they basically had a potluck wedding with the help of friends, on a rainy day, with homemade food and tents. It was charming. One friend/guest made a salad very similar to this one: beets roasted in one pan in the oven, lentils cooked in another at the same time, and the two brought together with the beet juices and a simple vinaigrette. It is a surprisingly delicious, elegant dish that needs nothing from the dairy department; don't even be tempted to add goat or feta cheese. I love the way it all takes on the ruby stain of the beets, too.
Preheat oven 425. Place whole beets in a 13 x 19 x 2 inch (or thereabouts) pan. Strew with onion slices, basil leaves, garlic. Drizzle with the oil; sprinkle with salt and pepper. Cover tightly with foil; cook, without uncovering, for 1 hour and 15 minutes.
While beets are cooking, place lentils in another similarly sized pan with 4 cups of the stock; tightly cover with foil.
Once the beets have cooked for 30 minutes (45 if you are using brown rather than French green lentils), place the pan of lentils in the oven. Check the lentils after they have cooked for 45 minutes (30 if you are using brown; they could get mushy). If the stock has been absorbed and the lentils are tender remove from the oven. Otherwise, continue to cook another 10-15 minutes or so, adding more broth if necessary to prevent the lentils from burning.
Meanwhile, make Simple Mustard Vinaigrette: In a jar, combine 8 tablespoons olive oil, 1 tablespoon Dijon mustard, 3 tablespoons red wine vinegar, 1/2 teaspoon salt, freshly ground black pepper. Screw lid on jar and shake vigorously until emulsified (the dressing, not yourself).
Once cooked, allow beets and lentils to cool, uncovered. Drain any excess broth from lentils if necessary. Remove beets from pan, reserving remaining delicious beet juice/onion/basil mixture. Peel beets and cut into 1-inch chunks. Gently combine lentils, juice/onion/basil mixture, and beets in a large bowl. Toss with about half the jar of Simple Mustard Vinaigrette; more to taste. Adjust salt and pepper. Serve at room temperature.