In a mixing bowl, blend together the vegetable oil and egg yolk until a homogenous mixture is formed.
Stir in the poppy seeds, honey, citrus juices (lemon and orange), apple cider vinegar, salt, pepper, and onion powder into the oil and egg mixture. Whisk vigorously to ensure all ingredients are fully incorporated.
Give the dressing a taste and adjust seasonings if desired. Depending on individual preferences, additional salt or pepper may be needed.
When finished, transfer the poppy seed dressing to an airtight container and store it in the refrigerator until ready to use.