Vietnamese Pickled Mustard Greens (Moms style)

Wash the mustard greens well then dry them in the sun until shrunk.
Cut the greens into 2 cm pieces.
Thinly slice shallots and ginger.
The trick is the more shallots the faster it turns sour.
Shallots can be replaced by spring onions (scallions).
Mix sugar, salt, shallots and ginger into the mustard greens.
Pour the rice water and warm boiling water into a large bowl.
According to my mom, using rice water to pickle mustard greens can make the greens turn yellow and sour more quickly.
Put the mustard greens into the warm water bowl.
Use a bamboo knitting sheet to compress and pebbles on top to weight down the greens in order to make them crunchy and not absorb the water.
In 1992, Mom visited HCMC and my whole family had a trip to Vung Tau.
While swimming in the sea, Mom saw some beautiful big smooth pebbles.
She, then, took some saying, "these are perfect for compressing the mustard greens when we pickle them.
Then she wrapped some pebbles and took them back to Son Tay and I also took 2.
Here they are.
The mustard greens are edible after 24 hours but they are still spicy.
However, they will be aromatic, yellow and sour after 48 hours.
Boiled pork is wonderful to be paired with mustard greens.
After 3 days, we can use these pickled mustard greens to cook soup with pork spare ribs, fish or it will be awesome to stir-fry with eggs to serve with hot rice.