A ternary plot only works if the three variables add up to the same constant.
There's no way to fit salad (0,1,0), soup (1,0,0), and steak (0, 0.5, 0) on the same ternary plot because the first two points add up to 1 and the last one add up to 0.5.
There's no way to fit salad (0,1,0), soup (1,0,0), and steak (0, 0.5, 0) on the same ternary plot because the first two points add up to 1 and the last one add up to 0.5.