In a large bowl, combine the tomatoes, garlic, pepper paste, cilantro, cayenne, cumin, lemon juice, and olive oil. Mix thoroughly with a spoon or spatula (do not use a whisk).
Heat a large stockpot over medium-high heat, add the tomato mixture, and cook until the mixture becomes fragrant and tomatoes begin to break down, about 1 minute.
Add the clams, stock, and basturma and bring to boil over high heat. Reduce the heat to simmer, cover, and cook, shaking the pot occasionally, just until all of the clams have opened. Using a slotted spoon, transfer the clams to serving bowls, leaving the broth in the pot.
Add the butter to the broth and check for seasoning. The basturma and the clams carry a good deal of salinity, and the soup will probably not need salt.
Ladle the broth over the clams, garnish each bowl with a handful of cilantro leaves, and serve with thick slices of grilled bread.
This recipe is by Garrett Malkonian from Soup for Syria. Soup for Syria is a collection of over 80 lavishly photographed soup and stew recipes. The international family of contributors includes celebrity chefs and authors such as Paula Wolfert, Alice Waters, Mark Bittman, Yotam Ottolenghi, and Anthony Bourdain. All the proceeds from the book’s sale go the United Nations Refugee Agency UNHCR. To support this effort you can purchase the cookbook by visiting www.soupforsyria.com .