3 lb. sm. zucchini, cut into 1/2" thick rounds
Salt
3 tbsp. butter
2 tbsp. vegetable oil
3 leeks (white part only), minced
1 sm. onion, minced
3 tbsp. red wine vinegar

Toss zucchini with salt in strainer. Top with plate and weight. Let stand 1 hour to drain. Rinse; drain well. Melt butter with oil in heavy large skillet over medium-low heat. Add leeks and onion and cook until softened, stirring occasionally, about 10 minutes, do not brown. (Can be prepared 8 hours ahead.) Add zucchini. Season with salt. Increase heat to high. Saute 3 minutes. Stir in vinegar and let boil until reduced to glaze.