Peel the cumbers, slice them in half lengthwise and remove any seeds with a teaspoon. Slice the cucumber into very thin slices crosswise, using a sharp knife or a mandolin. Trim the jalapeno, slice lengthwise, remove the seeds and finely mince.
In a large bowl combine the jalapeno, shallots, soy sauce, lime juice, sugar and stir to combine. Add in the cucumber and toss to combine. Transfer the mixture to a serving bowl or platter, top with the cilantro and the peanuts and serve.