Melt In Your Mouth, Grilled Teriyaki Wagyu Beef Sliders

This story will break your heart.  Shatter it.  Into millions of pieces.  I'm warning you.  I should probably just start penning a book called "Jenn's Super Sad Story."  Seth has been working nights and weekends (in addition to regular daytime hours). For months.  Then one glorious sunny Saturday, he decided to take a break and not go in for the day, just spend the day at home.  Even though I was feeling sluggish from not sleeping well and had a weird feeling in my throat, I was going to make the most of the day.  So we decided to do something low-key but fun - like grill!  We figured out what to grill, went out for lunch and afterwards obtained the necessary ingredients for our dinner.  And once all that happened, I realized I was sick.  Sore throat, headache, all that fun stuff.  So I helped make these sliders, but totally couldn't enjoy them the way they were meant to be enjoyed. Instead I savored some ice cream.  Since that never fails an ailing throat.  So that is the super sad story about how I was sick on the one day Seth was home and couldn't enjoy these sliders and "had" to eat ice cream instead.  I warned you that it would tug on your heartstrings in a profound way.  That said, Seth gave me some of this meat, fresh off the grill, and I can say it was absolutely melt-in-your-mouth amazing.  He insists they are the best sliders he's ever had, and still fresh in his mind a week later.  He even liked the pineapple on them!  And he hates pineapple!

Ingredients
2/3 cup mirin
1 cup soy sauce
4 teaspoons rice vinegar
1 teaspoon sesame oil
¼ cup brown sugar
7 cloves garlic, minced
1 tablespoon minced ginger
1 tablespoon minced jalapeno pepper
1 inch strip of orange peel

3/4 pound thinly sliced waygu beef
butter lettuce
Japanese cucumber, sliced
radish sprouts
Maui sweet onion, halved then sliced thinly
fresh pineapple slices, cored
scallions, chopped
jalapeno slices
Sriracha
mini kaiser rolls

Instructions
To make the teriyaki sauce:  Place the mirin in a medium pot and boil over high heat.  Reduce to medium low and add the soy sauce, rice vinegar, sesame oil, brown sugar, garlic, ginger, jalapeno, and orange peel.  Simmer for 20 minutes.  Refrigerate to cool.

Once the teriyaki sauce has cooled, marinate the beef.  Place the beef in a resealable bag and cover with the sauce.  Let it marinate for at least an hour in the refrigerator.

Preheat grill to high (roughly 400°).  Lay down grill-proof griddle and allow 3-4 minutes to preheat.  Working in batches, as necessary, place marinated beef on griddle and flatten out.  After 30 seconds to a minute, flip the meat and let cook for another 30 seconds to a minute before removing.  Both sides should be browned and only slightly charred.

Brush onion slices, pineapple slices, and cut sides of rolls with canola oil.  Place canola oil in a small bowl.  Using a paper towel or cloth, dip in canola oil and rub over hot grill grates to prevent sticking.  Grill the onions and pineapple on high heat until they have a light char on either side.  Place the rolls, cut side down, on the grates, and remove when lightly toasted.

To assemble the sliders:  Place a lettuce leaf on bottom slice of the bun.  Then layer cucumber slices, grilled pineapple, meat, grilled onions, jalapeno slices, scallions, radish sprouts, and top with a drizzle of Sriracha.