Remove center rib from silverbeet and discard. Blanch silverbeet in lightly salted boiling water for 30 seconds and then drain and plunge into ice water to stop cooking. Drain and set aside. To serve, saute shallots in oil until soft but not brown. Add blanched silverbeet and saute until tender but still with some texture. Season with salt, pepper and drops of lemon juice. Serve immediately.