Light your fire and let it burn down for 1 hour until you have nice coals or use hardwood charcoal.
Heat a large cast-iron frying pan until good and hot. Pat the rib eye dry with paper towel, then brush the meat with olive oil and sprinkle on one side with salt. Place the steak, salt-side down, in the pan and cook for 10 minutes or until well browned and crusty on the bottom. Season the top with salt, then flip over and cook for another 8 minutes.
Remove from the heat and let the fat render for a few minutes on each side, then transfer to a carving board, cover loosely with foil and rest for 10 minutes.
Place the squash in the hot pan and cook until tender. Remove and rest with the meat.
Combine the garlic and lentils (and the juices in the tin) in a small cast-iron frying pan. Bring to the boil and cook until the liquid has evaporated, and the lentils and garlic have softened. Remove from the heat and stir in the sour cream. Season to taste and spoon onto a serving plate.
Slice the steak and roughly chop the squash. Season and serve with the creamy lentils.