1. Grate the lemon zest. Squeeze the lemon.

2. In a large bowl, grate the ginger. Add the sambal oelek, soy sauce, oil, brown sugar, lemon zest, and lemon juice. Mix well with a whisk.

3. Cut the flank steak into 4 pieces. Transfer to the marinade bowl. Marinate in the refrigerator for 3 hours, turning the steak 2 times.

4. In a large non-stick skillet, place the steak pieces. Sear over high heat. Reduce the heat and cook for 45 minutes on each side. Remove from heat and let rest for 4 minutes.

5. Transfer the steak pieces to a cutting board. Slice each piece into thick slices. Serve with rice.