Place cucumber slices and onions in medium glass bowl. Set aside. Mix remaining ingredients in medium saucepan. Bring to boil on medium-high heat, stirring to dissolve sugar and salt. Reduce heat to low; simmer 5 minutes.
Pour hot liquid and spices over cucumbers and onions. Cool slightly. Cover.
Refrigerate pickles at least 2 hours before serving. Store in tightly covered container in refrigerator up to 2 months.