Place the chicken breast between two sheets of parchment paper and pound to an even thickness.
Season both sides of the chicken with sea salt, black pepper, and smoked paprika.
Heat the avocado oil in a grill pan over medium-high heat.
Grill the chicken breast for 5 to 6 minutes per side, or until the internal temperature reaches 165°F.
While the chicken rests, toast the sprouted grain bread slices until golden and firm.
In a small bowl, mash the avocado with a pinch of sea salt.
Spread the mashed avocado onto one slice of toasted bread and the Dijon mustard onto the other.
Layer the butter lettuce, tomato slices, and grilled chicken onto the avocado-spread bread.
Top with the remaining bread slice, cut diagonally, and serve immediately.