In a bowl, toss the beans with the vegetable oil and sugar.
Spread them in a single layer on an ungreased baking sheet. Roast them in the oven until crunchy and no longer soft in the centers, about 45 minutes. (Stir them a few times to prevent burning.)
Immediately toss the beans in a bowl with the cinnamon and salt. Cool and serve, or store in an airtight container at room temperature for up to a week.
For a savory snack, try tossing the beans with salt, paprika, and freshly ground pepper instead.