Before I try to answer your question I would like to take a minute to explain that you probably don't need as much protein as you think you do. Almost everyone I talk to overestimates their protein requirements. And not by a little. by two or three times. Thank the supplement industry and the livestock industry for the propaganda.
Although it varies depending on a few variables, you can usually figure that for every kilogram you weigh you need .8 gram of protein. Athletes do need more. Up to twice the amount for a regular person. In the USA we use
.36g per pound for regular people. and a much as .77g per pound for weight lifters.
You can also calculate your protein requirements as a function of your calorie intake.
Carbs - 50 - 60%
Protein - 10 - 20%
Fat - less than 30 percent.
Many dieticians go with the 60/20/20 rule
This works for athletes too. cause as your calorie intake goes up your protein goes up with it. An athlete can get a lot of protein simply by eating a lot of food. No need for supplements.
The Zone, a nutrition program developed in conjunction with the Stanford Swim Team put it at 40/30/30
anyway, sorry for the long diversion. If you read the Protein for Vegetarians article one of the point he makes is that if you eat enough calories you will get enough protein. And it almost doesn't matter what plant foods you eat. although you can get enough protein if you ate 2000 calories of lettuce - who could do that?
there are lots of other nutrients that are important besides protein. I can't remember why but we should balance our fat and protein intake (something about metabolism). And although leafy veggies, starchy vegetables, and fruits don't have a lot of protein per serving they have lots of the vitamins and minerals we need.
Now to actually answer your question. Beans, grains, nuts, and seeds are your most protein-rich plant-based foods. Tofu, tempeh, and endgame are the best.
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Sources
-https://www.verywellfit.com/how-to-calculate-how-much-protein-you-need-3955709
-https://wa.kaiserpermanente.org/healthAndWellness?item=%2Fcommon%2FhealthAndWellness%2Fconditions%2Fdiabetes%2FfoodBalancing.html
-https://www.foodnetwork.com/healthyeats/diets/2010/01/diet-101-the-zone-diet-a-k-a-40-30-30-diet
-https://michaelbluejay.com/veg/protein.html
-https://www.medicalnewstoday.com/articles/321474#15-best-vegan-proteins