Bring water to a near boil, pour over tea, and let steep 1 minute. Strain tea into a medium pot. Add onion, garlic, lemongrass, ginger, and chile; let cool slightly, then add chicken. Bring up to a simmer over medium heat, reduce heat, and gently simmer until the chicken is cooked through and a thermometer
inserted into the thickest part reads 160 degrees, about 7 minutes. Remove chicken from poaching liquid; strain liquid, discarding solids.
Place 4 cups of strained liquid in a medium pot. Add rice, olive oil, 1 teaspoon of salt, and black pepper. Bring to a boil, cover, and reduce to a simmer. Cook until all liquid is absorbed and rice is cooked through, about 50 minutes. Remove from heat and let stand 10 minutes.
While rice is cooking, remove chicken from bone and shred into large pieces. Keep chicken in remaining poaching liquid and reheat just before serving. Season with 3/4 teaspoon of salt, and black pepper. Serve rice with chicken moistened with some of the reserved liquid. Top with sliced scallions, cold cucumber spears, and a squeeze of lemon.