In a large non-stick frying pan, heat the oil over medium-high heat. Cook mince for 5 minutes, breaking it up with the back of a wooden spoon, until browned.
Add the stir-fry mix and cook for 3 to 4 minutes, or until vegetables are just tender. Add kecap manis and toss to coat. Season.
Meanwhile, prepare brown rice according to packet instructions. Set aside to cool for 1 to 2 minutes.
To serve, place lettuce cups onto a platter, top with a couple of tablespoons of brown rice and then the mince mixture. Drizzle with a little extra kecap manis (if desired) and top with mint leaves and sesame seeds.