To prepare a trout with fiddlehead ferns, you'll first need to gather your ingredients. You can find these ingredients at your local grocery store, or you can buy them online. To make the risotto, mix together 2 tablespoons of olive oil, 1 tablespoon of balsamic vinegar, and 1 teaspoon of thyme. Season the mixture with salt and pepper to taste. Heat the oil over medium-high heat and add the onion. Cook, stirring frequently, until the onions are translucent, about 5 minutes. Add the garlic and cook, whisking constantly, for 1 minute. Remove the pan from the heat. Pour in the wine and bring to the boil. Simmer the sauce for 2 minutes, then reduce to medium low and simmer for 30 minutes or until reduced by half.