Add lamb, panko, egg, shallot, garlic, parsley, oregano, mint, cumin & red pepper flakes to a large bowl. Use hands to mix the lamb, then season with salt & pepper.
Scoop lamb mixture into 1½ ounce portions. Roll into balls & place on a parchment paper lined baking sheet until all the mixture is used.
In a medium saucepan, combine bulgur and 3 cups of water. Bring to a simmer over medium heat then cover & lower heat to medium-low & cook until tender (~10 min). Remove from heat & let stand, covered (additional ~10 min). Fluff with a fork.
In a skillet over medium heat add olive oil & heat through. Working in batches, add meatballs to skillet. Cook until meatballs are just cooked through & brown on all sides (~8 min). Remove to a plate. If needed, add remaining olive oil to pan & repeat with remaining meatballs.
Spread tzatziki on plates or bowls & add a scoop of cooked bulgur. Divide meatballs onto plates & top with chopped cucumber & chopped fresh mint. Serve immediately.