First, prepare the rich ganache centers. Fill a small saucepan about halfway with water and bring it to a gentle simmer on the stove over medium heat. Combine the semi-sweet chocolate and bittersweet chocolate in a large, glass heat proof bowl and set it over the simmering water to let it melt. Stir it occasionally with a heat proof rubber spatula. Once it is pretty well melted, pour in the sweetened condensed milk and stir it all together until it is thick and smooth. Turn off the heat and stir in the tequila and lime zest thoroughly. Cover the bowl and chill it in the refrigerator for 2 to 2 1/2 hours to let it set enough to mold it.
Line a sheet tray with a silicone mat or parchment paper. When the chocolate filling is done chilling, use a heaping 1/2 tablespoon measure to scoop the perfect amount of the mixture out and roll it into a small ball. Keep scooping and rolling until the mixture is used up and line them up on the sheet tray as you make them. With the heaping 1/2 tablespoon measure, you should get about 40. Put the tray in the freezer for 20 minutes to let the centers firm up completely.
When the centers are just about ready to come out of the freezer, transfer the milk chocolate into a large microwave safe bowl. Microwave it for about a minute and a half to completely melt it. Stir it well to make sure it is completely smooth. Line another sheet tray with another silicone mat or parchment paper. Roll each of the centers in the melted chocolate to coat them. Use a fork to fish them out so that the excess can drip back into the bowl. Nudge the coated centers off of the fork with a toothpick onto the sheet tray and use the toothpick to score around the truffle so that there isn't a big blob on the bottom of them. When all of the centers are coated, sprinkle them all with the lime sea salt on top. Put the tray in the refrigerator to let the chocolate coating completely harden. When you are ready to serve them, put them in a pretty bowl and let them sit for 15-20 minutes at room temperature so that they aren't rock hard. Then enjoy the decadence!