Walk forward once the fight starts and throw the boomerang right before you jump off then pull your sword out in midair. Do one roll out of the fall slightly right then instantly jump attack Dangoro, he will then curl up and you can sidehop to equip the Iron boots on faster and throw him in the lava.
Below is a video of fighting Dangoro with roll stabs for all the hits. The first hit is slower than mentioned above but the second and third has audio ques to listen for.
For the second hit wait until the first beat stop playing.
For the third hit wait until just after the second beat starts playing.
It should be noted that in 100% which will have shield bash, you can use shield bash to make him expose his stomach so you can spin attack him to make him curl up, this is faster than waiting for him to attack if you mess up the strategies mentioned above.