Prepare mashed potatoes by boiling potatoes, then mashing them with butter and herbs.
Cook rice according to package instructions.
Toss salad ingredients (cucumber, lettuce, tomato) with lemon dressing in a bowl.
Serve the beef stir-fry with mashed potatoes, rice, and salad on the side.
Notes
For extra flair, consider garnishing with chopped herbs or a sprinkle of sesame seeds. Leftovers can be stored in an airtight container in the refrigerator for 3-4 days. Reheat gently to avoid overcooking the beef.