Mix minced meat, breadcrumbs, mustard, egg, sunflower seeds, salt, and pepper. Season to taste. Shape into 4 meatballs, then press each flat. Place 1 teaspoon pesto in the center of each, fold the edges over, and shape back into meatballs.
Heat roughly 2 tablespoons oil in a pan over medium-high heat. Fry the meatballs for 10-12 minutes, turning to brown both sides, until the internal temperature reaches 74 °C (165 °F).