Hi, I'm Dan Garcia. I'm going to explain this flamenco technique called pulgar-indice-pulgar, which means thumb-index-thumb. The rhythm I figure that we're going to use is the triplet, which means you fit three notes on the beat.
First note is going to be with the thumb. The second note is with your index and the third note is again with your thumb, and then your first one is with your thumb again. That means you have to play your thumb twice in a row. So here it goes. We go one-two-three, one-two-three, one-two-three, one-two-three, okay?
When you put it on over a melodic pattern, we get something like this. Okay a good way to practice this technique is by doing chromatic scales with your thumb, and using your index, which should always be leaning on your first string anyway. And all the way up and down the neck and have fun doing this, so this is the pulgar-indice-pulgar technique. Enjoy it.