Add the yogurt, vinegar, sugar, onion, mustard, and salt to a blender and process on high for 20 seconds. With the blender still on, slowly stream in the oil. Add the poppyseeds and pulse the dressing 3-4 times on low until all the ingredients are fully combined. Recipe makes about 1 cup of dressing or 8 servings.
Recipe by Love Grows Wild at https://lovegrowswild.com/2015/01/poppy-seed-dressing/