1. Bring 2 quarts of water to a boil. Add the pearl onions and cook for 2 to 3 minutes. Remove the onions from the water with a slotted spoon and cool in a bowl of ice water.
2. Add the beans to the boiling water and cook for about 2 minutes or until tender but not mushy. Remove from the water and cool in the ice water.
3. Peel the onions.
4. Melt the Plugrá Butter in a medium sauté pan. Add the onions and cook until the Plugrá Butter begins to brown. Add the beans, mint and tarragon, and sauté until heated through, about 1 minute. Season with salt and pepper.