Place the dates and cashews in a small bowl and cover with boiling water. Let sit 10 minutes, then drain and lightly pat dry. Place in a food processor fitted with a steel blade. Pulse in long bursts until the mixture forms a sticky paste and only small bits remain, stopping to scrape down the bowl a few times as needed. Add the coconut sugar, vanilla extract, and kosher salt. Pulse a few times to incorporate, then continue blending until you have a fairly smooth “dough.” If the dough is too sticky to handle, place the food processor (with the dough inside) in the refrigerator or freezer for 10 to 15 minutes to firm up.
Line a baking sheet with parchment paper. With a small scoop or spoon, scoop a portion of the dough, then roll it into a ball with your hands. Place the ball on the baking sheet. Repeating with remaining dough. (You will have 12 to 15 truffles total, depending upon how large you roll them.) Place in the freezer to firm up for 10 to 15 minutes.
Meanwhile, to make the chocolate topping, place the chopped chocolate in a heatproof bowl, then set that bowl over a pan of simmering (not boiling) water. Make sure that the bottom of the bowl and the water do not touch. Melt the chocolate, stirring often. When the chocolate is almost completely melted but you can still see a few pieces, remove the bowl from the pan. Add the coconut oil and stir until smooth and glossy, letting the residual heat of the chocolate melt the mixture the rest of the way.
Remove the truffles from the freezer. To completely dunk the truffles in chocolate: working one at a time, dip a truffle into the melted chocolate. Use two forks to roll it around so it’s coated, then use the forks to remove the truffle from the chocolate and lightly tap away any excess chocolate. Place the truffle on the parchment paper, then top immediately with sea salt. Be sure to sprinkle it right away—the chocolate sets fast! Repeat with remaining truffles. Let sit at room temperature for a minute or two to set. Enjoy!