Wash and dry the cucumbers. If using English cucumber, peeling is optional. For Persian cucumbers, no peeling is needed. Using a sharp knife or a mandoline, thinly slice the cucumbers into rounds or half-moons. Place the sliced cucumbers in a large mixing bowl.

If using, thinly slice the red onion and add it to the bowl with the cucumbers. Roughly chop the roasted peanuts and set aside about 1/4 cup for garnish. Roughly chop the fresh cilantro.

In a separate small bowl, whisk together the creamy peanut butter, low sodium soy sauce, rice vinegar, sesame oil, honey/maple syrup, grated fresh ginger, minced garlic, and sriracha or chili garlic sauce until smooth.

Gradually add water, 1 tablespoon at a time, to the dressing, whisking constantly until it reaches your desired pourable consistency. It should be thick enough to coat the salad but not too gloopy. Taste and adjust seasoning if needed (more spice, more sweetness, more tang).

Pour the prepared dressing over the sliced cucumbers and red onion in the large mixing bowl. Add most of the chopped cilantro and the main portion of the chopped peanuts. Toss gently to ensure all the cucumber slices are evenly coated with the dressing.

Transfer the Spicy Peanut Cucumber Salad to a serving dish. Garnish with the reserved chopped peanuts, remaining fresh cilantro, and a sprinkle of red chili flakes (if using). Serve immediately for the best crispness, or chill for 10-15 minutes to allow flavors to meld.