In a large saute pan over medium high heat place chopped onion, grated carrot, chopped bell pepper, garlic, and 2 tablespoons ketchup.
Add teaspoon of oil and about 1 cup of water and cook until onions start to become softened and translucent, about 5 minutes.
Add cooked lentils, oregano, 8 tablespoons more ketchup, sugar, salt to taste, Worcestershire and mix together until heated through.
Add more ketchup, sugar, salt or pepper to taste and remove from heat. If mixture is too thick, add tablespoon of water and mix in until you reach the desired consistency.
Open hamburger bun and scoop 1/3 -1/2 cup bean mixture onto bun half. Top with pickles. Serve while beans are still warm.