Peel one cucumber. Run a fork down the outside, if you wish, and taste a bit to see if it's bitter. Slice it. If it's a bit mushy or bitter, you can improve the flavor by laying it out in a bowl and salting lightly.
Dressing: 1 tsp siracha (Sambal is a decent brand - beware that this is hot, so cut back as needed. You can substitute 1 clove garlic, crushed,) 1 tsp vinegar, 3 tsps soy, 2 tsp sesame oil. If using garlic, I'd zap it in the microwave to mild the garlic a bit and let cool.
You could also try peanut butter thinned with water, 1 tsp chili paste to give it some fire, and some green onions.
To serve, sprinkle your cucumbers with toasted sesame and then dip in the sauce or drizzle the sauce over.