Wash the cucumbers under cool running water and pat dry to remove excess moisture.

Slice the cucumbers into 1/4-inch thick rounds using a sharp knife.

In a small bowl, whisk together the fish sauce, lime juice, and palm sugar until the sugar dissolves completely.

If using raw peanuts, heat a dry skillet over medium heat and toast the peanuts for 2 to 3 minutes, stirring frequently, until fragrant. Let cool.

Thinly slice the shallots, mince the garlic, and slice the red chili into thin rings.

In a large mixing bowl, combine the sliced cucumbers, shallots, garlic, and chili slices and toss gently.

Pour the dressing over the cucumber mixture and toss well to coat all pieces evenly. Let sit for 2 to 3 minutes to allow flavors to meld.

Stir in the chopped peanuts and fresh cilantro just before serving, reserving a small handful of peanuts and cilantro for garnish.

Serve immediately in a chilled bowl to maintain maximum crunch and freshness.