Place the smashed juniper berries and chopped lemongrass in a reusable tea bag and set aside.
Drizzle the bottom of a large pot with olive oil. Add the onion, celery, carrots, garlic, beef fat, and bay leaves. Cook over medium heat for about 5 to 7 minutes, stirring occasionally, until the vegetables begin to soften.
Add the tea bag with the juniper berries and lemongrass. Stir in the grape tomatoes and cook for another 2 to 3 minutes.
Stir in the lentils.
Pour in the chicken broth, and hot water.
Add the ginger, thyme, sage, and black pepper. Stir well.
Bring the soup to a boil. Reduce the heat to low, partially cover the pot, and simmer for 35 to 45 minutes, stirring occasionally, until the lentils are tender. If the soup gets thicker than you like, add a little more water or broth.
Turn off the heat, remove the bay leaves and the tea bag. Season with salt. Stir in the chopped callaloo or other leafy greens. Cover the pot for 2 to 3 minutes to let the greens wilt.
Taste and adjust the salt and pepper if needed.
Serve with grated Parmesan cheese, sliced scallions, chopped parsley, or your favorite combination of the three.