If you choose not to use tendon, just skip this part of the procedure and go straight to shaping & boiling meatballs.
Start by washing tendon, patting dry before soaking with 2 Tbsp of wine (I used vodka) for 5-10 minutes. This will help removing any strange odor.
Pressure cooker: boil enough water, then add tendon and 1 Tbsp of salt, pressure cooked for 20 minutes so that tendon is almost done, but not fully tender. Vent manually.
Regular pot: boil tendon with 1 Tbsp of salt, but cook longer, 40-60 minutes
Prepare an icy cold water bath with 1 Tbsp lemon/lime juice, upon remove tendon, dip and soak them immediately in the cold water bath.
When the tendon is fully cool, cut it down to shorter length and throw into your food processor, pulse a few times to chop into smaller chunks, but not paste.
Grate ginger and finely mince garlic (if using) and mix together with the tendon bits.
Wrap tendon bits and store in the fridge until use. Do this while you're waiting for the beef mixture to chill in the freezer to save time.
Once you finished the second regrind paste step, take out tendon bits, divide and mix together the beef mixture. Use a stand mixer with a flat beater to achieve this. Don't prolong mixing time more than 30 sec, add crushed ice to cool the mixture down if you're in a hot climate.