Bistek Tagalog, regular

Bistek Tagalog is the local version of beefsteak, sauteed in soy sauce and calamansi, with caramelized onion rings.

Usually I like my bistek chunky, but this time I decided to make it with really thin slices of beef. 

The cooking method is pretty pretty much the same, with a few variations.

400 grams very thinly sliced beef (I used sirloin)
6 tablespoons light soy sauce
3 tablespoons calamansi juice
5 tablespoons low fat milk
1 to 2 teaspoons black peppercorns, lightly smashed

1 medium sweet onion (Vidalia), sliced into rings
water, as preferred
salt and pepper, to taste
cornstarch slurry

Marinate the tenderloin pieces in soy sauce, calamansi juice, milk and peppercorns about 15 to 20 minutes.

Heat oil gently and caramelize the onion rings (this may take some time over a gentle heat so as not to burn the onions).  Remove the onions and increase heat to medium or medium-high.  Using a slotted spoon, lift the meat pieces and place into the frying pan.  Stir fry a few seconds (they will cook fast since they're sliced thinly).  Pour in the marinade and cook until simmering.  Adjust the seasonings, as preferred.  I like a saucy dish so I almost always add a little water then  thicken with cornstarch slurry.  Add in the onions and toss to coat everything in sauce.  Remove from heat and serve immediately.