From Ground: Make sure to water the miner's lettuce lightly only to dampen the soil, ensuring the plant's root ball remains intact. This would make extraction easier. Carefully dig around the plant using a spade or shovel, taking care to keep the root ball undamaged. Once a sufficient trench around the miner's lettuce has been dug, slide the shovel or spade under the root ball to lift the plant. Handle the plant gently by its root ball.
From Pot: First, water the miner's lettuce slightly until the soil is damp, not wet. If the plant is too tightly rooted, you may need to turn the pot sideways, or upside down while supporting the plant. Tap the rim of pot against a hard object to loosen the plant and the soil around it. Hold the plant gently at the base and pull it out, ensuring that the root ball stays intact.
Seedling Tray: Keep the soil around the miner's lettuce uniformly moist before starting this process. Apply gentle pressure to the underside of the tray, and lift the seedling by its leaves at the same time. Be careful not to damage the delicate roots.