This is the same recipe used for my Marinated Tomato Slices. Get the freshest cucumbers you can find or use the English version.

1 cup vegetable oil (I use canola)
1/3 cup vinegar – white, rice, or tarragon (not cider vinegar)
1/4 cup minced fresh parsley or 1 Tbsp. dry
3 Tbsp. minced fresh basil or 2 tsp. dry
1 Tbsp. sugar
1 tsp. kosher salt
1/2 tsp. black pepper
1/2 tsp. dry mustard powder
1/2 tsp. garlic powder
1 medium sweet onion, sliced thinly into rounds
4+ large cucumbers peeled and sliced thin

In a small bowl or a jar with a tight-fitting lid, whisk or shake-up the first 9 ingredients.
Layer the cucumbers and onions in a shallow, non-plastic dish. Pour the marinade over; cover and let refrigerate for a minimum of 2 hours.