BARCELONA, Spain (AP) — Once the potatoes are cooked and the eggs half set, Sonia Castel places a plate over the sauté pan and instructs one of her students to grab the handle.

Castel, 63, thrums on the counter for a drumroll as Mason Kauffman, one of a group of American exchange students in the cooking workshop, holds the plate steady and steels himself to flip the pan. After a countdown of 3, 2, 1, cheers erupt as he makes the flip, sliding the eggs back into the pan to finish cooking a Spanish tortilla, or omelet.

“I was so nervous,” says Kaufmann, a junior at New Hampshire’s Plymouth State University, smiling broadly.

After each student has a turn, Castel pulls them into a hug and practically demands a kiss on the cheek.…