Skirt steak fajitas with chimichurri sauce

Ingredients

• 2 lbs skirt steak
• 3 tbsp olive oil
• 11 oz soft flour tortillas (6 inch)
• 1 tomato (sliced)
• 1 small bermuda onion (sliced)
• 1 oz watercress (washed, dried and coarsely chopped)
• 1/2 cup olive oil
• 3 tbsp white vinegar
• 2 jalapeno peppers
• 1 oz flat leaf parsley
• 3 tbsp cilantro
• 1 clove garlic
• 1 bay leaf
• sea salt
• black pepper