When in Spain, the lunch on the go usually is a bocadilla.
As long as you put it on a baguette you can call it a bocadilla.
My Mama Española used to make me one of these everyday. The most common is the tortilla española-- Spain's famed potato omlet. She'd slice it thin and stuff it in between a fresh baguette with a schmear of aioli. Sometimes it still be warm from the morning. Her other varitations of onions and cheese, or sauteed peppers were equally delicious but nothing stood out like the bocadilla made with Manchego and Membrillo. The first time I ate this I could describe the flavors: fruity, salty, nutty, with hints of citrus, but had no idea what exactly I was eating.
Turns out the Spanish have been doing the Manchego-Membrillo collabo for quite sometime. Manchego is a common table cheese made from sheep's milk and its best room temperature so you can really get the full effect of its nutty, salty flavor. Membrillo is a fruit paste made from quinces with splashes of lemon juice. The two flavors together are quite stunning and bright and a good way to change up things for your tastebuds as we burst into Spring.