Fill a pot with enough water to fully cover the frankfurts.
Bring the water to a rolling boil over high heat.
Reduce heat to keep a gentle boil.
Add the frankfurts to the pot.
Boil until heated through, typically 5–7 minutes.
For firmer casings, boil 3–5 minutes; for softer casings, boil 7–10 minutes.
Remove with tongs.
Drain briefly and serve immediately.