Combine bulgur and water in a medium saucepan. Bring to a simmer. Cover and cook on low heat until tender, 10 to 12 minutes. Drain and rinse under cold water. Transfer to a large bowl.
Meanwhile, heat 2 Tbsp. oil in a large skillet over medium-high heat. Add chicken, garlic powder, and 1/2 tsp. salt. Cook, stirring occasionally, until the chicken is cooked through and just browned, 6 minutes. Let cool slightly.
Add the chicken and any juices from the skillet to the bowl with the bulgur. Add tomatoes, scallions, parsley, and mint; stir to combine. Whisk lemon juice and the remaining 4 Tbsp. oil and 1/2 tsp. salt in a small bowl. Add to the bulgur mixture and stir to combine.
To make ahead: Prepare bulgur (Step 1) and refrigerate for up to 1 day.
Tip: Bulgur is made by parboiling, drying, and coarsely grinding wheat berries. Look for it in the natural-foods section of large supermarkets, near other grains.