Sauté the ground beef over high heat for 6 to 7 minutes, remove any excess grease from the pan and stir in the taco seasoning. Continue cooking for 1 to 2 minutes, until cooked through, adding a little water for moisture, if needed. Stir in the lentils and remove from heat.

Meanwhile, preheat the oven broiler, arrange the bun halves on a baking sheet and gather any other optional toppings, if using. 

Top each bun with taco mixture. To make 8 melts, use 1/3 generous cup each, to make 6 melts, use 1/2 generous cup each. Sprinkle a handful of cheese (about 2 tablespoons) over each melt.

Add the melts to the broiler and broil for 2 to 3 minutes, until the cheese is melted. Serve. We love them all on their own but sometimes I will set out fun toppings using whatever I have on hand.