Beef Jerky

Did a batch of jerky this past weekend. Still trying to get consistent results in taste and texture. This one came close in the taste catagory but some of the meat was tough. Here's the recipe and a couple of pictures.

2 lbs sirloin or flank steak (using sirloin)
4 tablespoons black pepper ( i reduced to 3)
1 cup soy sauce (i used low sodium soy)
1 tablespoon tony chachere's
2 tablespoons worcestershire sauce
2 teaspoon brown sugar
1 teaspoon tiger sauce (hot pepper sauce)
1 teaspoon chili powder
1 teaspoon garlic powder
1 teaspoon onion powder

Placed the meat on the smoker at a temp of 155* using a mix of pecan and hickory woods. It took about three hours.