Artemis BJJ (Easton Road), Can Sönmez, Bristol, UK - 11/09/2019
From the low mount, your attacking options are limited. I've found the most reliable is the ezequiel choke, which has the advantage of being low risk and also opening up a route to high mount even if you don't get the choke. To begin, you need to get one arm under their head. Many people will just give you that space as they try to escape, but if not, you can press into their neck to get them to raise their head.
Once you have an arm under the head, you can progress to the next stage. To get the choke, you need to block off both sides of their neck. For the first side, you're going to use your gi. With the hand you have under their head, grab your free sleeve. Pull it tight to the nearest side of their neck. Remember that it is the sleeve that is applying that half of the choke, not your hand. You therefore need to pull that sleeve across and into their neck. You may need to grip the sleeve with less fingers to increase your range, so that you are pulling gi material into their neck.
Curl your free hand in past their chin, moving it across their neck. Keep reaching, until you can make a chopping motion down into the other side of their neck. Make sure you're pressing into the side of their neck, not the throat (although crushing the windpipe may still get a tap, it isn't as efficient). To finish, pull on the sleeve as you chop. If you need to increase your leverage, raise up slightly (some people will even put a foot by the head to really drive). However, be aware that giving them more space could lead to an escape.
Obviously it isn't going to be that easy in sparring. They're going to be blocking you with their hand, trying to buck you off, disrupting your attack any way they can. To avoid that, there are a couple of options. One is to slip your arm inside their defending arm, pushing your arm through, then driving your elbow to the mat. You can then slide that arm back to trap their arm to their side, clearing the way for your choke attempt. Alternatively, they may give you the opportunity by pushing on your knee.
Fill up the space by sticking your head right next to theirs. Use this as both a means of control and a barrier against their efforts to get a hand back inside. Stay low, then gradually slip in your second hand. Again, they may give you the opportunity by bridging. If they are staying really tight, use your head to push into their skull, aiming to get them to turn it away. When that space appears, follow your head with your hand, then slip through for the choke.
Getting the ezequiel can be tricky due to the limited amount of material your sleeve provides. An alternative is to use the lapel instead. The first step is to get an arm under their head. Pull out either their gi lapel (preferable) or your own, then pass it to the hand you have under their head. This variation is similar to the lapel attack I like to do from side control, where you feed your gi to the hand you have under their head (something you can set up from mount too, dismounting to side control for the finish). Even more fun, if they are being super-defensive and crossing their arms to block a choke from mount, that's where the ezequiel variation comes in.
Pull their gi lapel up and over their bent arm, feeding it to the hand you have under their head. Bring your other arm underneath that lapel, cutting the hand down by the side of their neck, like you would for a standard ezequiel. You can then finish the choke pretty much as normal. If you start off with the gi lapel slightly loose, it's easier to slip your other hand under, before tightening it right up.
Teaching Notes: Make sure you get a turn of their head, which means you will probably need to switch your head back over theirs in order to expose the side of their neck. Grinding the skull across is useful for initially clearing a route for your hand, as well as then turning their head back the other way. Also, you can rotate your arms around their neck to get to the sides, should they have their head either turned in the wrong direction or be facing straight up.
On the gi tail, I could talk more about rising up for leverage, though it's important to note that people can also do this from a lower position, preferably due to less space. Saulo goes up on one foot, IIRC, which applies to the application of both versions. Worth checking that again before I teach this next time.