Step 1

Preheat oven to 300°. Trim the ends off of 1 onion. Cut in half through root end, peel and discard skin, then coarsely chop. (No need to sweat the knife work here—it's all going to get blended anyway.) Transfer chopped onion to a medium bowl.

Step 2

Using the flat side of chef’s knife, smash 3 garlic cloves. Peel and discard skins, then coarsely chop. Transfer to the bowl with the chopped onion.

Step 3

Using a spoon, peel 2" piece ginger. (We always like to use a spoon to peel ginger, which is way better for navigating all of those nooks and crannies than a vegetable peeler.) Thinly slice and add to bowl with onion and garlic.

Step 4

Trim a handful of cilantro leaves with tender stems; set aside for serving. Coarsely chop remaining stems and transfer about ¼ cup chopped stems to bowl with onion. Clear your cutting board.

Step 5

It’s time to break down your squash! (We promise it’s not as scary as it sounds.) Trim off both ends of 1 butternut squash, then cut through where the neck meets the bulb. (This makes it easier to peel.) Peel both pieces of squash with a vegetable peeler. Cut squash neck and bulb in half lengthwise. Using a spoon, scoop out seeds from each half of the bulb; discard seeds. Place squash pieces cut side down on board and cut each piece in half lengthwise. Cut squash crosswise into 1"-thick slices. Again, you don't need to worry about beautiful knife work here, but it's good for the pieces to be similarly sized so they cook at the same rate.

Step 6

Vigorously shake 13.5-oz. can of coconut milk for a few seconds so everything gets well mixed. Open can and set aside 3 Tbsp. milk to swirl over finished soup.

Step 7

Heat 2 Tbsp. oil in a large Dutch oven or saucepan over medium. Add onion mixture, ¼ tsp. red pepper flakes, and 1 tsp. salt and cook, stirring occasionally with a wooden spoon, until onion is translucent and soft, 5–7 minutes.

Step 8

Add squash and give everything a stir to coat. Add 3 cups water, or enough to just submerge the squash, remaining coconut milk in can, and 2 tsp. salt, then stir to combine. Raise heat to high and bring soup to a boil.

Step 9

Once soup is boiling, reduce heat to medium-low and simmer, stirring occasionally, until the vegetables are very tender, 12–14 minutes.

Step 10

Meanwhile, prepare your garnishes. Spread ½ cup coconut flakes on a rimmed baking sheet. Toast in oven until golden brown, about 5 minutes. (If you can't find big coconut flakes, shredded is okay, too, but it will probably take less time to toast. Just make sure to avoid any pre-sweetened stuff.) Keep an eye on them—coconut flakes can go from golden to burnt in seconds. Cut 1 lime into wedges; set aside for serving. Using a fork or citrus reamer, juice the second lime into a small bowl.

Step 11

You’re almost ready to blend—so let’s do this! First things first: set up your workstation. You’ll need your pot of soup, blender, a large bowl, a ladle, and a clean kitchen towel all within arm’s reach. Using ladle, fill blender pitcher no more than halfway with equal parts broth and vegetables (if you fill it up, it will overflow as it blends!). Now, here’s the most important step of this entire recipe: When you secure the blender lid, make sure there is a vent for the steam to escape (many blender lids come with removable vents). If you skip this step, the lid will blow off and you will end up with soup on every inch of your kitchen.

Step 12

Holding the lid down with a folded kitchen towel, carefully blend soup, starting from the lowest speed and working your way up to high, until smooth and silky, 10–15 seconds. Transfer to a large bowl. Repeat, working in batches, until all soup is blended.

Step 13

Wipe out Dutch oven and return to stove. Pour soup back into pot and heat over medium, stirring occasionally, until you can see steam rising from the pot. (You may be tempted to serve the soup straight from the blender, but it loses a lot of heat in the blending process and gets lukewarm. Trust us—you want to reheat it.) Stir in lime juice. Taste and add more salt if needed.

Step 14

Ladle soup into bowls. Top with a swirl of reserved coconut milk, toasted coconut flakes, and cilantro. Serve with reserved lime wedges.

Step 15

Do Ahead: Soup and toppings can be made 4 days ahead. Store in separate airtight containers and chill.