Lady Clarke of Tillypronie includes two versions of Country Captain from the ultraminimalist school in her cookery book from 1909, consisting only of chicken, onions and curry powder. The first cuts a cold, cooked bird into serving pieces on the bone and tosses them in a teaspoon of curry powder seasoned with salt and moistened with water. Then she browns 2 thinly sliced onions in 4 Tablespoons of butter, adds the seasoned chicken, covers the pan and cooks, stirring to prevent burning, until the chicken browns in the “oniony butter.”
The other version is, if possible, simpler still:
“Joint a cold fowl, and rub well into the pieces about 1 Tablespoon of curry powder. Slice 2 large onions into a frying pan with some butter and a little salt, also the fowl. When the onions are browned the dish is ready.”
Obviously the quality of your curry powder is paramount for either version, neither of which is particularly recommended. They do, however, demonstrate the range of Country Captain recipes.