炊く and 炊事: Rice, the cooking tool, and the activity
Read the rice object and the clay-pot tool in 土鍋で米を炊く. Compare those roles with 炊事 as a meal-preparation activity someone takes charge of and with 炊事の後 marking cleanup afterward.
米を and 土鍋で with 炊く
「今夜は土鍋で二合の米を炊く。」 — “Tonight I will cook two measures of rice in an earthenware pot.” 米を is what is cooked, and 土鍋で names the tool used. 二合 gives the amount of rice. 今夜は places the action tonight rather than reporting completed cooking in the past.
「母が炊いてくれたご飯はふっくらしていた。」 — “The rice my mother cooked was fluffy.” 母が炊いてくれた modifies ご飯. ふっくらしていた describes how the rice was fluffy, while the first example refers to tonight’s cooking.
炊事 as an activity name
「山小屋では当番が炊事を担当する。」 — “At the mountain hut, the person on duty handles cooking.” 炊事 names meal preparation that the person on duty takes charge of. Compare this activity as the object of 担当する with the concrete 米を炊く verb construction.
「炊事の後、鍋や食器をきれいに洗った。」 — “After preparing the meal, we washed the pots and dishes thoroughly.” 炊事の後 locates washing the pots and dishes after meal preparation. That activity name is not confined to the single action of cooking rice.
An object, a tool, and an activity
米を炊く specifically describes cooking rice. With 炊事を担当する or 炊事の後, follow the verb or time phrase connected to the broader meal-preparation activity name.
土鍋で names the cooking tool, while 米を names the object. Their roles distinguish cooking the rice from doing something to the pot itself. The mountain-hut example also keeps 炊事 from being limited to one’s own home.
What is the cooking object and what is the tool in 「今夜は土鍋で二合の米を炊く」?
Show the answer and why
米を identifies the rice being cooked, and 土鍋で identifies the clay pot used. 二合 gives the rice quantity. Read those verb roles separately from 炊事 as the activity name.