Wash the flat mustard leaves and pat dry. Soak under the sun for 1 hour or until wilted.

Meanwhile, prepare the rice water by combining rice and water in a pot. Cover and cook the rice in medium heat until soft.

Combine salt and mustard leaves in a bowl. Gently mash the mixture. Arrange in a resealable jar.

Place a mesh strainer over the jar. Pour the rice water from the pot. Note: the soft rice should be filtered by the mesh. We only need the water for this process.

Cover the jar. Let it stay in room temperature for 4 to 6 days.

Serve as an appetizer or use an ingredient to cook fish, egg, and other dishes. You can stock it in cooler temperature (50 to 55F) for the flavor to develop further.

Share and enjoy!