This has got to be a trap, that food actually looks edible.
The unnatural blue-green color is just a fanart gimmick. In the canon/pseudo-canon materials (aside from the anime), they only refer to her curry as being basically like normal curry, but she adds a few really strange ingredients or spices that make it taste very "ethnic" (Kirishima's euphamism). In the anime, she just dumps a "secret ingredient" into Kongou's normal curry.
The unnatural blue-green color is just a fanart gimmick. In the canon/pseudo-canon materials (aside from the anime), they only refer to her curry as being basically like normal curry, but she adds a few really strange ingredients or spices that make it taste very "ethnic" (Kirishima's euphamism). In the anime, she just dumps a "secret ingredient" into Kongou's normal curry.
I like that interpretation better than the usual gag. It's a bit saner, the idea that she's not actually poisoning people, she's just into some kind of weird fusion flavor profile that most folks don't cotton to. Like guacamole ice cream.