Instructions
Step 1
Make the stock: Peel and devein the shrimp, then set aside, reserving the shells. (You should have about 2 cups of shrimp shells.) To a large pot, add the shrimp shells, fish sauce, salt, cilantro, culantro, lemongrass, peppers, garlic, onion, and 8 cups of water. Bring to a boil, then turn the heat to low and simmer for 20–30 minutes.
Step 2
Meanwhile, make the mofongo: To a large deep skillet fitted with a deep-fry thermometer, add the vegetable oil and turn the heat to medium-high. When the temperature reads 375°F (you can also test the temperature by dropping a small of piece of plantain into the oil; it should sizzle and float on contact), working in batches, gently add the plantains and fry, turning occasionally with tongs, until golden brown on all sides, about 5 minutes per batch. Using tongs, transfer the plantains to a paper towel-lined plate. Repeat with the remaining plantains.
Step 3
While the plantains fry, to a small skillet over medium heat, add the olive oil. When it’s hot and shimmering, add the garlic, turn off the heat, and cook in the residual heat, stirring occasionally, until evenly browned, 1–2 minutes. Set aside.
Step 4
To a pilón or mortar and pestle, add 1 cup of the fried plantains, a quarter of the sautéed garlic and its oil, and season to taste with salt. Using the pestle, mash the plantains, continuously scraping the sides into the center, until the ingredients are fully incorporated and the texture resembles a loose dough, about 5 minutes. Using your hands, scoop out the mashed mixture and form into an individual mofongo, roughly the size of a baseball. Transfer to a soup bowl, then repeat with the remaining plantains and garlic. (You should have about 4 balls total.)
Step 5
Make the shrimp: Strain the stock through a fine-mesh sieve into a medium pot, discarding the solids. Bring the stock to a boil, then season to taste with more fish sauce and salt. Add the shrimp, remove from the heat, and allow to sit until the shrimp are no longer translucent, 2–3 minutes.
Step 6
Using a slotted spoon, divide the shrimp among the bowls with mofongo. Pour 1 cup of stock into each bowl, around or over the mofongo. Garnish with the cilantro, avocado, lime, and hot sauce, and serve immediately.