Marinated beet and summer squash salad

2 medium-size beets, cooked, peeled and thinly sliced
4 bunching onions, thinly sliced
1/4 cup olive oil
3 Tbsp tarragon vinegar
1/2 Tbsp sugar
2 Small yellow summer squash (or zucchini, or a combination), cut into 1/4-inch slices
1 Tbsp minced dill
3/4 cup sour cream
Salt and black pepper
2 Scallions, each with 3 inches green top, coarsely chopped

Directions: Toss together the beets and onions with 1/8 cup olive oil, 2 tablespoons vinegar and 1/2 tablespoon sugar. Refrigerate for at least 2 hours. In another bowl toss together the squash slices, the remainder of the oil and vinegar, and the dill. Refrigerate for at least 2 hours. Just prior to serving, drain the squash and toss all the vegetables together with the sour cream. Season to taste with salt and pepper, adding additional sugar and vinegar if desired for a more distinctive sweet-and-sour taste. 3 servings