Wash the chicken breast fillets, pat dry, and cut into bite-sized pieces. Heat oil in a pan over medium-high heat. Fry the chicken pieces for 8-10 minutes, stirring occasionally, until the internal temperature reaches 74°C (165°F). Remove and set aside.
Drain the mushrooms and bamboo shoots. Fry the drained mushrooms, bamboo shoots, and finely chopped onion in the same pan over medium-high heat for 5 minutes until crisp.
Return the chicken to the pan and stir in the sour cream. Add 1 teaspoon mustard, 2 teaspoons vegetable stock, curry powder, paprika powder, salt, and pepper. Stir well and cook for 2-3 minutes until heated through.