2 serrano chiles (remove seeds for a milder curry)
3 cloves garlic
1 tablespoon peanut or expeller-pressed canola oil
1 3/4 pounds sirloin tip steak, cut into 3/4-inch cubes
1/2 teaspoon fine sea salt, plus more to taste
1 cinnamon stick
1 1/4 teaspoons coriander seeds
1 1/4 teaspoons ground cumin
1 teaspoon ground turmeric
1 (13.5-ounce) can light coconut milk
1 (14.5-ounce) can diced tomatoes, drained
1/2 teaspoon sugar
1 pound red potatoes, cut into 1-inch pieces
1/3 cup packed cilantro leaves
In a large skillet with a tightly fitting lid, heat oil over high heat. Sprinkle steak with salt. Add half the steak pieces to the skillet and cook, stirring occasionally, until lightly browned. Transfer to a bowl with a slotted spoon; repeat with remaining steak. Set aside.
Return the skillet to medium-high heat and add cinnamon, coriander, cumin and turmeric; stir for 10 seconds and then add the onion and chile mixture. Simmer for 1 minute and then stir in coconut milk, tomatoes and sugar. Add the beef back in, cover the skillet, and simmer 40 minutes. Stir in potatoes and continue to simmer until beef and potatoes are very tender, about 20 minutes more; remove the lid during last 10 minutes of simmering if you would like a thicker sauce. Remove cinnamon stick; taste curry and add more salt if desired. Serve garnished with cilantro.