500 calories of broccoli takes far more energy to produce than 500 calories of meat. Broccoli is bulky, it's mostly air & water and indigestible starch. It takes many pounds of broccoli to get 500 calories, whereas 500 calories of steak is only a few ounces. So unless that broccoli is hyper-local, transportation costs alone may make it worse. Even if it is hyper-local, I still suspect that broccoli is a worse way of converting solar energy into human energy than cows are.
Environmentalists usually compare meat to calorie dense vegetable sources, like grains & legumes. That's fair because it's impossible for a human to eat enough broccoli to stay alive -- it takes about the same amount of energy just to digest the broccoli as you get from it.
The "standard" metric for meat conversion is that it takes 12 pounds of wheat to make 1 pound of beef. But that's very misleading. Cows generally don't eat wheat. Naturally raised cows eat grass. Cows eating grass in midwestern North America is probably the closest we can get to its natural ecosystem, which used to be dominated by mammoths eating grass until they were killed off, then by bison eating grass until they were killed off. But humans can't eat grass. Cows have four stomachs and a rumination habit that ensure that it is efficiently digested.
Even feedlot cattle are much more efficient than the 12-1 metric would have you believe. The feed barley and feed corn varieties that are grown to feed cattle yield at rates 2-8 times better than the high-protein wheat varieties fed to humans. Not too mention the fact that when you feed corn to cattle you feed them the entire plant. Humans just eat the seeds.