Prepare the fiddleheads by washing them under water, peeling off any brown papery skin (most won't have that but some might), and slicing off any brown ends. Fill a large bowl with cold water and add the fiddleheads, swishing them around with your hands to remove any dirt. Discard the water and repeat this process another time.
Bring a pot of water to a boil. Add the fiddleheads and cook them for 10 to 15 minutes until tender. Alternatively, you can bring a couple inches of water to a boil in a large pot, insert a steamer basket with the fiddleheads, cover, and steam them for 10 to 12 minutes until tender.
**NOTE: The recommendation to cook them for 10-15 minutes is based on food safety standards for fiddleheads. Due to the possibility of toxic compounds in fiddleheads causing stomach upset and issues, it’s recommended to boil them for 15 minutes or steam them for 10 minutes. You can read more about this here and here. However, there is some debate in the culinary world about how long fiddleheads need to be boiled; many chefs choose to blanch them for shorter periods of time (i.e. 5 minutes) so that they don’t get too soft. In addition, small fiddleheads tend to soften more quickly than larger ones, so the degree of softness can vary depending on the specific fiddleheads used. Some readers have experimented with a shorter boiling time for this recipe and have had no issues. If you want to try a shorter boiling time at your own risk, you can start checking them for doneness around 5 to 8 minutes. You can also read through the comments section below the post for tips from other readers. My recommendations to cook them for 10 to 15 minutes remain and are in accordance with food safety standards.**
After boiling, drain and rinse the fiddleheads in a colander. Alternatively, you can transfer the fiddleheads to a bowl of ice water to completely stop the cooking process. Many people find that this also helps preserve their texture. Drain and pat dry before the next step.
In a large skillet, heat the olive oil and 1 tablespoon of the butter over medium heat. Add the garlic and the fiddleheads, and cook for a few minutes. Stir in the other tablespoon of butter, lemon juice, and lemon zest. Cook for another few minutes, and serve warm. Enjoy!