Butterfly the chicken breast to ensure even thickness and pat dry with a paper towel to help the coating stick.
In a shallow bowl, whisk together the almond flour, dried oregano, garlic powder, sea salt, and black pepper.
Press each side of the chicken firmly into the almond flour mixture until it is evenly and thoroughly coated.
Heat half of the olive oil in a non-stick skillet over medium heat and cook the chicken for 5-6 minutes per side until golden brown.
While the chicken is cooking, whisk the remaining olive oil, lemon juice, and Dijon mustard in a small jar until emulsified.
Slice the cucumber into rounds, halve the cherry tomatoes, and thinly shave the red onion.
Toss the mixed greens, cucumber, tomatoes, and red onion in a large bowl with the prepared lemon vinaigrette.
Slice the crispy chicken into strips and arrange them over the salad to serve immediately.