Tortilla Española con Sparrago

• 1 lb white, red, fingerling, or other "waxy" potatoes.
• 1/2 small yellow onion, chopped
•  3/4 lb asparagus, snapped and cut into 1" to 2" lengths
• 2 tbs pure olive oil
• 1/2 tsp salt
• 6 eggs, beaten
• 10" to 11" nonstick pan with lid, 2 spatulas, flipping tool (see below)

Optionally peel the potatoes, and slice them into 1/4" thick slices.  If the potatoes are large, slice them in half as well; each piece should be about the size of a half-dollar and twice as thick.

Heat the pan over medium-low heat with the olive oil.  Drop in the sliced potatoes, and cook them gently for 8 minutes, using the two spatulas to turn them over every 2 minutes.  Add the onions, asparagus and salt, and cook for another 12 minutes, turning as before.

At this point the potatoes should be cooked all through.  Make a hole in the middle of the mixture and pour the eggs into it, then stir the mixture around to make sure the eggs get evenly distributed, especially on the bottom.  Turn down to low heat and cover with the lid, and cook for about 10 minutes.

At this point the eggs should be mostly firm.  Now comes the hard part; flipping the tortilla.  There's a number of ways to do this, all of them awkward:  (1) flip it into another, preheated pan; (2) flip onto a greased pizza peel and slide back in; (3) flip onto a rimless cookie sheet and slide back in.  The only easy way is to buy yourself one of those twinned omlet pan things.

Cook the bottom for about 3-4 minutes.  Slide onto a serving plate, and let cool.  When cool, slice into wedges and serve with aioli or Romesco sauce.