Here's a good protein entree from my 1918 cookbook. I like the reference to a 'vegetable grinder'. In modern kitchens, we can just use a blender or food processor.

The recipe doesn't really explain what the 'right consistency' is. So I'd say it's thick enough to hold a ball shape but not too dry. You want these to be tender. Here's the general directions for making croquettes.

Lentil Croquettes

Run cooked lentils through a vegetable grinder. Add 1 chopped Spanish onion, 1/2 grated nutmeg, 1/2 cup cream, salt 2 eggs and cracker crumbs to make the right consistency. Shape into croquettes and brown in the oven.