Michaela's Steak Sandwich

Ingredients

• 1/3 cup olive oil, divided
• 1/4 cup fresh lemon juice
• 1 large jalapeno pepper, seeded and minced
• 2 cloves crushed garlic
• 2 tablespoons freshly chopped cilantro (or parsley)
• 1 teaspoon steak seasoning
• 1 1/2 pounds skirt steak
• 3 tablespoons butter, divided
• 4 waxy potatoes, peeled and sliced thin
• 2 large red onions, sliced into half moons
• 4 long sandwich rolls, split
• 8 slices pepper Jack cheese