Fill a saucepan with a few inches of water and bring to a bare simmer. Combine the chocolate, coconut oil and sea salt in a medium heatproof bowl and set over the pan (do not let the bowl touch the water). Cook, stirring occasionally, until the chocolate is melted and the mixture is well combined, 5 to 10 minutes.
Remove the bowl from the pan and let the mixture cool at least 15 minutes before pouring on top of ice cream (or you can dip your ice cream in the mixture instead). Transfer any remaining sauce to an airtight microwave-safe container and refrigerate up to 3 months. To remelt, uncover and microwave in 10-second intervals, stirring, until pourable.