In a large pot or Dutch oven, cook chopped bacon over medium heat until crisp. Remove with slotted spoon, then drain on paper towel and set aside, reserving bacon grease in the pot.
Add rinsed lentils, cumin, smoked paprika, vegetable broth, and salsa verde. Bring to a boil, then reduce to a gentle simmer and cover.
Meanwhile, heat a skillet over medium-high, then drizzle with olive oil. Slice a head of garlic in half and place cut sides down, along with halved onion, poblano, serranos, and tomatillos. Roast undisturbed for 4 minutes, then flip and roast an additional 4 minutes or until evenly charred.
Place poblano in a ziploc bag and let it steam for 5-10 minutes. Squeeze roasted garlic from skins and add to soup along with charred onion and tomatillos. Peel and discard poblano skin, then roughly chop poblano and add to pot with de-stemmed serranos. Cover and simmer for 25-30 minutes or until lentils are tender.
Heat butter in a small skillet over low heat, then add 1 large yellow onion (thinly sliced) and a pinch of salt. Cook over very low heat for 20-30 minutes, stirring every 10 minutes until golden brown.
Add fresh chopped cilantro, then puree the soup until creamy using an immersion blender. Stir in coconut milk, lime juice, and salt and pepper to taste.
Serve in individual bowls topped with a swirl of coconut milk (optional), caramelized onions, crumbled bacon, and garnish with chopped cilantro.
Notes
Char = flavor! Don't be too worried about the veggies burning.
Garlic cloves may require additional roasting time (and an extra drizzle of oil) if they aren't easily squeezed out of their skins. Roast for an additional 5 minutes first, then proceed as necessary.
Make sure to thoroughly rinse your lentils and to check for foreign objects like pebbles, as these can sometimes be present.
You can use pre-cooked lentils to save a bit of cook time.
If you do, consider reserving a portion of the cooked lentils to be added during step 6 for added texture.
You can thin lentil soup with bacon by adding a splash of water, if necessary.
Store leftover soup in an airtight container in the fridge. Store bacon in a separate container and add just before serving, for best results.
Bacon and lentil soup freezes beautifully and can be safely stored in the freezer for 3-6 months.
Reheat soup gently over medium-low heat, stirring frequently. If reheating from frozen, allow it to thaw in the fridge overnight first.