Coarsely chop preserved black beans.

Combine preserved black beans, red pepper flakes, salt, sugar, and Sichuan pepper (if using) in a heat-proof jar.

Heat peanut oil in a saucepan over medium heat.

Test the oil's heat by adding a shallot bit; it should sizzle.

Add diced shallots to the oil and fry until golden brown, maintaining a simmer.

Transfer the hot oil and shallots to a glass measuring cup.

Immediately pour the hot oil and shallots over the pepper flake mixture in the jar.

Let the mixture cool and settle.

Stir to combine well.

Enjoy immediately or store in a cool, dark place for up to a month for best flavor.