Vietnamese Shaking Beef (Bo Luc Lac)

Name: Vietnamese Shaking Beef (Bo Luc Lac)
Cuisine: Chinese, Japanese
Ingredients: 1 1/2 lbs beef top sirloin (fat trimmed and cut into 1″ cubes); 5 cloves crushed garlic; 1 tbsp agave or sugar; 1 tbsp oyster sauce; 1 tbsp fish sauce; 1 tsp sesame oil; 1 tsp thick soy sauce; 1/2 cup rice vinegar; 1 1/2 tbs sugar (or agave); 1 1/2 tsp kosher salt; juice of 1 lime; 1/2 tsp kosher salt; 1/2 tsp fresh cracked pepper; 1 small red onion (thinly sliced); 4 cups watercress leaves or mixed baby greens; 2 to matoes (thinly sliced); 1 tbsp canola oil (divided)