Combine green beans and cider in a microwave-safe bowl; cover with plastic wrap. Cook in microwave on high for 5 minutes; stir beans. Return to oven and cook until tender, 5 more minutes. Remove beans with a slotted spoon and transfer to a serving bowl; reserve cider.
Heat olive oil in a small skillet over medium heat; cook and stir bacon bits and onion in the hot oil until onion is tender, 5 to 10 minutes. Pour cider from green beans into the skillet; simmer until liquid is reduced, 5 minutes.
Spoon bacon mixture over green beans. Season with salt and black pepper.
