Mix the ground flaxseeds and water in a small bowl and set aside.
Saute the onion in a little water over medium heat until it's soft and slightly translucent.
Add the garlic and saute for 30 seconds.
Add the celery and carrots and saute for a couple of minutes until softened. Add a splash of water if the pan appears dry.
Transfer the cooked vegetables to a large mixing bowl. Add the cooked lentils, Italian seasoning, 2 Tablespoons of ketchup, Dijon mustard, panko breadcrumbs, flaxseed mixture, and salt and pepper, to taste. Fold together until well combined.
Fill the muffin pan cups with the lentil mixture and pat each one down tightly.
In a small bowl, mix the ¼ cup ketchup and balsamic vinegar. Brush each lentil meatloaf muffin with a little of the mixture.
Bake for 25 to 30 minutes.
Remove the pan from the oven and allow the muffins to rest 5 to 10 minutes. Carefully remove and serve.
Serving: This recipe makes 12 mini meatloaf muffins. A good rule of thumb is to allow 2 muffins per guest. You can easily double or triple the recipe if you're feeding a crowd.Storing: You can prep the vegan meatloaf a day in advance and refrigerate in the muffin pan until ready to bake. In addition, the cooked muffins can be refrigerated up to 3 days or frozen up to 3 months. Reheat in the microwave oven or enjoy cold.Top tip: Allow the meatloaves to rest for 5-10 minutes before removing them from the pan to prevent them from falling apart.