Why did the German command manage to seize the initiative in 1942? What goals did it pursue?

The whole point is that at that time the Soviet command believed that the enemy would concentrate its main attack in the direction of Moscow. At the same time, the Germans were more concentrated in the eastern direction. Insufficiently stubborn resistance of the Red Army in this direction and the miscalculation of the command of the USSR became the reason for the interception of the initiative by the enemy. The Germans planned to cut off the USSR from the oil fields, take Stalingrad and call on Turkey and Japan to their side.