Take your smaller diameter line like braid and double it over and then 1) begin by wrapping it around the larger diameter line like your fluorocarbon leader 6 times. Once you’ve done that, 2) hold the loop and pass the fluoro leader tag end up through the loop at the end of the wraps. Then moisten and snug the knot by pulling on both tag ends and mainlines all together, being careful not to let the braided tag end to slip through the knot as it snugs down.
It will take a few tries to get the knot down, but once you do, you can tie it really fast. It’s incredibly strong and makes a really small knot that will pass easily through guides.
More Fishing Knots:
Read our Wired2fish Fishing Knot Guide
Read our 4 Tips on Tying a Good Fishing Knot