Combine ingredients in a large pot. Mix well to dissolve salt and sugar. Cool to room temperature. Immerse split hens in cooled brine, cover, and refrigerate for 4 hours. Combine basting mixture ingredients and set aside.
Prepare grill and bring heat up to medium (350°). Brush grates with oil so birds don’t stick. Cook hens skin-side up for 25 minutes, basting once. Flip and cook for an additional 15 minutes, basting again before finished. Delicious when served with potato salad or roasted Brussels sprouts.