Melt olive oil and butter in large pot over medium heat. Add onion and carrot and cook until tender and onion is translucent, about 5 minutes. Add the lentils and stir for a couple of minutes to “toast”. Add the tomato paste and stir to incorporate. Add tomato, red pepper flakes, and fresh and dried mint. Stir to incorporate. Add the stock and water and bring to a boil. Cover and reduce heat to medium. Simmer 15-20 minutes until the lentils break apart and become incorporated in the liquid. Blend with immersion blender until smooth. Salt to taste.