Line and 8-inch (20cm) square pan with plastic wrap. Combine whipping cream, butter and sea salt in a saucepan and bring to a boil. Remove from the heat and set aside.
In another saucepan, combine sugar, corn syrup and water and cook on high heat (without stirring) until a candy thermometer reads 360F (185C) or mixture turns a dark caramel color. This can take anywhere from 5 to 10 minutes, depending on your stove and the kind of saucepan you are using.
Remove from the heat and, standing back in case mixture splatters, stir in cream mixture with a long-handled spoon. Return saucepan to high heat and cook, stirring constantly, until candy thermometer reaches 250F (120C). Remove from the heat. Add lemon juice and stir until well combined. Pour into prepared pan and let set overnight.
Unmold caramel from pan, peel off plastic wrap, and cut into desired shapes using a lightly oiled knife. Place caramels on a tray lined with parchment paper or a silicone mat. Using a fork, dip caramels into tempered chocolate and slide on another tray lined with a silicone mat. Optionally while chocolate is still wet, finish with a few grains of sea salt. Let set for about 4 hours, then store in an airtight container in a cool, dry place for up to 3 weeks.