Heat a wok or large skillet over medium heat. As the pan is heating, add rice and kaffir lime leaf and cook, stirring constantly, until the rice becomes dark golden brown, about 10 minutes. (Note: The rice will smoke quite a bit as it cooks and will smell very fragrant, almost burned. As long as none of the grains show signs of burning / turning black in spots), keep going until all of the grains are an even, deep golden brown color. If any rice grains do start to burn, be sure to reduce the heat.)
Take the wok / skillet off the heat and continue stirring until the pan cools down a bit.
Let the rice sit in the pan until completely cool.
Transfer the rice and kaffir lime leaf to a coffee / spice grinder or use a mortar and pestle to grind until it forms a smooth, even powder that still has some texture. (The grains within the powder should be slightly uneven which gives the powder a perfect texture for laab.)
Store toasted rice powder in a sealed jar at room temperature for up to 2 weeks or in the refrigerator for up to 2 months.