My Best Steak Sandwich

2 large sandwiches:

2 baguettes
1 lb shredded beef
Salt, pepper, and Worcestershire to taste

1 large onion, thin sliced
2 Tbsp oil or butter
1 Tbsp Worcestershire

Green sauce:

1 bunch cilantro
1 bunch parsley
2 jalapeno or serrano pepper
3-4 cloves garlic
1 tsp salt, or more to taste
1 tsp ground cumin
1 tsp ground coriander
2 Tbsp red wine vinegar vinegar
1/2 cup olive oil

1/2 cup mayo
1 Tbsp harissa paste
Pinch of salt
Squeeze of lemon