Wash cucumbers, cut in half and scoop out seeds (leave skin on). Run cucumbers through juicer. Pour juice into small, low-sided skillet or saute pan, whisk over medium heat until just bubbling around edges. Add slurry and cook, whisking to desired consistency; don't cook too long. Whisk in lime juice and white wine, remove from heat. Add dill and green onion, whisk in gently. If using, whisk in butter until blended; serve.