Rinse the lentils under cold water until the water runs clear, then set aside.
Dice the onion finely and mince the garlic cloves. Heat a large skillet over medium heat and add a tablespoon of oil until shimmering.
Add the diced onion and minced garlic to the skillet. Sauté for about 3-4 minutes until fragrant and translucent, stirring frequently and listening for the gentle sizzle.
Stir in the tomato paste and cook for another minute, allowing it to darken slightly and release a rich aroma.
Add the rinsed lentils to the skillet and pour in the vegetable broth. Stir everything together, ensuring the lentils are coated in the flavorful mixture.
Bring the mixture to a gentle simmer, then lower the heat to medium-low. Cover partially and cook for about 25-30 minutes, stirring occasionally, until the lentils are tender and the sauce has thickened.
During simmering, add a splash of Worcestershire sauce, cumin, and smoked paprika. Taste and adjust seasonings as needed, adding more spices if desired.
Once the lentils are tender and the sauce is thick, turn off the heat and let it rest for 5 minutes to allow flavors to meld and the mixture to thicken further.
While the mixture rests, lightly toast the buns until golden brown, either in the same skillet or in a toaster.
Spoon the hearty lentil mixture generously onto the toasted buns, allowing the sauce to soak in slightly but still hold its shape.
Serve the Lentil Sloppy Joes hot, with your favorite sides like pickles or a simple salad. Enjoy this messy, flavorful, plant-based comfort food!