Wash the asparagus, cut off the woody ends, peel the lower third. Cover half of the asparagus and cook in boiling salted water for about 8 minutes. Cut the rest into slices and cook for about 5 minutes. Drain
Peel and chop the onion. Peel, wash and coarsely grate the potatoes. Heat oil in a coated pan (approx. 20 cm Ø). Steam both in it for 10-15 minutes until soft (do not brown). Seasoning
Whisk eggs, salt and pepper. Mix in well with asparagus slices. Leave to stand over a low heat. Turn the tortilla with a flat lid. Fry for 2-3 more minutes. Take out, let cool down if necessary
Cut ham into strips, tortilla into about 12 pieces. Serve with ham and asparagus spears
Drink: cool sherry fino, for example Tio Pepe by González Byass