In a medium size bowl whisk to combine the olive oil, lime juice, tequila, jalapeños, garlic and cilantro. Add the chili powder, cumin and 1 teaspoon of the salt. Whisk again. Place the chicken breast into the bowl and toss to coat in the marinade. Cover and chill. Leave the chicken to marinate for 8 hours or overnight.
Heat a quarter-sized amount of canola oil in a large skillet until shimmering. Place the chicken breast in the skillet and sear on both sides until golden.
Using a fine mesh strainer, strain the marinade and add it to the skillet. Discard the solids. Pour in the stock and bring to a boil. Reduce the heat to a simmer and let the chicken cook for 10 minutes, turning once, or until the juices run clear. Transfer the chicken to a cutting board and tent with foil. Set aside.
Stir the remaining salt and the brown sugar into the chicken's poaching liquid. Increase the heat and bring the mixture to a boil.
In a small bowl whisk to combine the cornstarch and water. Pour the mixture into the boiling poaching liquid. Cook until the mixture is thick enough to coat the back of a spoon, stirring constantly.
Shred the chicken with two forks and pour the sauce over top. Toss to coat. Keep warm until ready to serve.
In a cast iron skillet heat the canola oil until shimmering. Add the tortillas and fry until crisp and golden brown. About 2-3 minutes a side. Transfer the fried tortillas to a plate lined with paper towel and let drain.
Spread a little of the Smoky Pepita Spread on each tortilla. Top the spread with a large spoonful of the chicken followed by a few slices of avocado, tomato halves, red onion slices and fresh cilantro. Serve immediately with lime wedges and beer.