This is basically a reverse Bulgarian split squat, but this variation is both safer and more difficult. The key is take a 15-second pause before your reps. (Not shown in video because, well, it's boring to watch a 15 second pause!)
Front-Foot Elevated Paused Split Squat
By elevating the front foot, you'll lean forward slightly to hammer the legs through an extended range of motion without a break from tension. This increases the hypoxic environment, stimulating more muscle and metabolic damage for growth while building tons of unilateral strength and stability.
As an auxiliary movement, perform 3-5 sets of 6-10 reps per leg, starting with that all-important 15-second pause at full depth. Rest 30 seconds between legs and 60 seconds between sets.