Step 1Heat 2 Tbsp. extra-virgin olive oil in a large Dutch oven or other heavy pot over medium. Cook 2 medium onions, chopped, 4 garlic cloves, finely chopped, and one 2" piece ginger, scrubbed, finely chopped, stirring occasionally, until onions are softened, 6–8 minutes. Add 2 tsp. ground cumin and ¾ tsp. ground turmeric and stir to coat onions. Season with freshly ground black pepper. Add ½ preserved lemon, rinsed, seeds removed, finely chopped, and 3 Tbsp. double-concentrated tomato paste and cook, stirring often, until tomato paste is darkened in color, about 4 minutes.
Step 2Add 8 cups good-quality low-sodium vegetable or chicken broth and 2 cups red lentils, rinsed, and bring to a boil, skimming foam from surface as needed. Reduce heat to medium-low, partially cover, and simmer, stirring occasionally, until lentils are very tender and soup is almost creamy, 35–45 minutes.
Step 3While the lentils are cooking, heat 2 Tbsp. extra-virgin olive oil in a small saucepan over medium. Cook 4 garlic cloves, thinly sliced, stirring often, until golden and starting to crisp, about 3 minutes; remove pan from heat. Using a slotted spoon, transfer garlic chips to paper towels, leaving oil behind. Lightly season garlic chips with kosher salt. Stir 1 tsp. Aleppo-style pepper into infused oil in pan and set aside.
Step 4Remove soup from heat and stir in 1 cup torn mixed tender herbs (such as basil, dill, cilantro, and/or parsley). If soup is too thick, thin with water. Taste and add up to ½ preserved lemon, rinsed, seeds removed, finely chopped, if desired (you may find the soup lemony enough as it is). Season with more salt if needed.
Step 5Ladle soup into bowls. Top with garlic chips and more herbs and drizzle over reserved pepper oil.
