Chorizo is a popular Spanish sausage made from pork, seasoned with paprika and other spices. It is often grilled or pan-fried and is known for its rich and smoky flavor. In El Retiro Park, you can find vendors selling chorizo sandwiches, where the sausage is served in a crusty bread roll with toppings like grilled onions and peppers. It's a delicious and satisfying meat option to enjoy while exploring the park.