Melt the butter in a small frying pan on medium heat. Add the minced shallots and mushrooms and cook gently for 3 to 4 minutes until softened.
1 large shallot, 1 tbsp unsalted butter, 6 oz mushrooms
Stir in the minced garlic and the mushrooms. Continue to cook on medium heat until the mushrooms are cooked through and have given up some, but not all, of their moisture.
1 clove garlic
Stir in the mixed herbs. Remove from heat. Place in a bowl and quickly chill to cool.
1 tsp mixed herbs
In a large mixing bowl, place the ground turkey, parsley, Dijon mustard, balsamic vinegar, lemon zest if using, mayonnaise, salt, black pepper, and the cooled mushroom shallot mixture.
Using your clean hands gently mix the turkey and other ingredients together until well combined. Don't over mix.
Form meatballs, 1 to 1 1/2 inches wide, depending on your preference. Smaller meatballs with be easier to serve as a one-bite appetizer, larger meatballs for a main dish. Place meatballs on a tray.
Place the formed turkey meatballs on a tray
Heat olive oil in a large sauté pan on medium low to medium heat. Once the oil is hot, place the meatballs in the pan, allowing for space around each meatball and brown all over.
1 tbsp extra virgin olive oil
Do not crowd the pan; if your pan isn't big enough, cook the meatballs in batches. Gently cook the meatballs until cooked through, turning them frequently so that they get lightly browned on all sides. If meatballs are not browning, increase the burner heat a little.
Add meatballs to the sauce. Simmer for a minute to warm the meatballs through. Sprinkle with a little chopped parsley to serve.