In a large saucepan, heat 1/4 cup of the olive oil. Add the fennel and cook over moderate heat for 2 minutes. Add the cucumbers and cook for 2 minutes. Add the wine and saffron and cook until the wine has reduced by half, about 2 minutes. Add the vegetable stock and cook until the fennel is tender, 10 minutes.
Meanwhile, season the salmon pieces with salt and pepper and dust them lightly with the flour. In a large nonstick skillet, heat the remaining 1 tablespoon of olive oil. Add the salmon pieces and cook over moderately high heat until barely cooked through, about 3 minutes per side. Transfer the salmon pieces to the saucepan and cook for 1 minute. Season the salmon with salt and pepper and serve at once.