Grease an 8- or 9-inch square pan.
Put the chickpea flour, stock, and rosemary in a medium saucepan; season with salt and pepper and whisk to combine. Cook over medium heat, whisking constantly, until the mixture is very thick, 7 to 10 minutes.
Spread the chickpea flour mixture as evenly as possible into the greased pan, cover with foil or plastic wrap, and refrigerate until firm, at least 1 hour.
Put at least 2 inches of the canola or light olive oil in a large, deep pot over medium-high heat.
Cut the chickpea flour cake into ½-by-3-inch strips.
Add one of the strips to the oil to test whether it’s hot enough; the oil should immediately bubble vigorously.
Working in batches, cook the remaining strips until deep golden brown, 3 to 5 minutes.
Transfer the strips to paper towels to drain, season with salt, and serve hot.
