Lightly spray a medium frying pan with oil. Heat over high heat. Add mince. Cook, breaking up mince with a wooden spoon, for 5 minutes or until browned. Add seasoning mix. Cook, stirring, for 1 minute. Add ¾ cup cold water. Bring to the boil. Reduce heat to medium. Simmer, uncovered, for 5 minutes or until mixture is thick. Remove from heat. Cover to keep warm.
Meanwhile, combine flour and a pinch of salt in a bowl. Make a well in centre. Whisk milk and egg in a jug. Pour milk mixture into flour mixture. Whisk until smooth. Stir in half the chopped coriander.
Heat a large non-stick frying pan over medium heat. Brush pan with a little melted butter. Pour 1/3 cup batter into pan. Swirl pan to cover base. Cook for 3 to 4 minutes or until bubbles appear on surface. Turn. Cook for 2 to 3 minutes or until golden and cooked through. Transfer to a plate. Cover with foil to keep warm. Repeat with remaining batter to make 4 pancakes.
Combine avocado, tomato, lime juice and remaining coriander in a bowl. Place pancakes on plates. Top with mince mixture, guacamole and sour cream. Serve topped with extra coriander.
