Moving laterally is great way to work the glutes on the side of your pelvis (known as the gluteus medius) as well as the inner thighs. These muscle groups help stabilize the pelvis and should be considered part of the core.
Start with your feet directly under your hips. Step your right foot wide to the side coming into a lunge with your left fingers touching your right foot. Your right knee shouldn't go beyond your right toes. Keep your chest lifted and your weight in your heels.
Push into your right foot to return to standing, then lunge sideways to the left to complete one rep.