Steak Enchilada Bowls with Sweet Potato Rice

Preheat broiler to high; place a rack in upper third of oven and place a baking sheet on the rack.

Working in 2 batches, pulse sweet potatoes in a food processor until they break down into rice-size pieces. You should have about 4 1/2 cups. Rub 1 Tbsp. oil over steak; sprinkle with 1/8 tsp. salt and 1/4 tsp. pepper. Place on the hot baking sheet and broil for 5 minutes. Turn the steak over and broil until an instant-read thermometer inserted in thickest part registers 130 to 135 degrees F for medium-rare, 3 to 5 minutes more (see Tip). Transfer to a cutting board; tent with foil and let rest for 10 minutes.

Meanwhile, heat 1 Tbsp. oil in a large skillet over medium heat. Add onion, sprinkle with 1/8 tsp. each salt and pepper, and cook, stirring occasionally, until tender and lightly browned, about 3 minutes. Add garlic; cook, stirring often, for 1 minute. Add spinach, one large handful at a time, stirring, adding more and sprinkling in 1/8 tsp. salt as you go. When all the spinach is in the pan, cook, stirring often, until the excess liquid has evaporated, 2 to 3 minutes. Transfer to a bowl; cover and set aside.

Add the remaining 2 Tbsp. oil to the skillet and heat over medium heat. Add the sweet potato "rice," and the remaining 1/8 tsp. salt and 1/8 tsp. pepper; cook, stirring, for 1 minute. Add broth. Cover, reduce heat to medium-low, and cook, stirring once or twice, until the "rice" is tender, 6 to 8 minutes.

Slice the steak against the grain. Divide the "rice" among 4 bowls. Top with the spinach, steak, avocado, and radishes. Drizzle each bowl with 2 Tbsp. enchilada sauce and sprinkle with cilantro, if desired.