Not really. It puts the emphasis on the process, but you'd probably prefer the dinner to be actually prepared til the end, right? And that needs the perfective "zrób".
"Rób" can also have the general meaning, meaning of regularity: "Rób mi obiad codziennie" - "Make me dinner every day".
"Obiad" is not really lunch. "Obiad" is dinner or supper (depending on where you're from). Lunch is between breakfast and dinner.