Rinse the cured beef tongue under cold running water. Place in a large saucepan, pour in the white wine, and add cold water until the tongue is covered by about 1 cm. Bring to a boil over medium heat.
While the tongue comes to a boil, wash, clean, and roughly chop the soup greens and onions.
Once boiling, add the chopped vegetables, garlic, bay leaves, cloves, peppercorns, allspice, and juniper berries to the saucepan. Reduce heat to low, cover, and simmer for 2 hours 30 minutes to 3 hours.
Remove from heat and let rest for 10 minutes until cool enough to handle but still warm.
Carefully peel off the skin from the tongue.
Slice the tongue and arrange on a serving plate. Drizzle with melted butter and serve.