Adjust rack to top position and preheat oven to 425 degrees. Wash and dry produce.

Halve bell peppers lengthwise; remove ribs and seeds. Place on a baking sheet and drizzle each half with oil; rub all over to coat. Season with salt and pepper, then arrange cut sides down.

Roast on top rack until browned and softened, 15-18 minutes.

While peppers roast, heat a large drizzle of oil in a large pan over medium-high heat. Add panko and cook, stirring, until golden brown, 3-5 minutes. 

Turn off heat; transfer to a small bowl. Season with salt and pepper. Wipe out pan. 

Meanwhile, halve, peel, and dice onion into ½-inch pieces. Drain and rinse beans. Peel and mince or grate garlic. Roughly chop cilantro. Quarter lemon.

In a small pot, combine couscous, stock concentrate, and ¾ cup water (1½ cups for 4 servings). Bring to a boil over medium-high heat. Once boiling, cover and reduce to a low simmer. Cook until couscous is tender, 6-8 minutes. Drain any excess water if necessary.

Keep covered off heat until ready to use in Step 5.

Heat a drizzle of oil in pan used for panko over medium-high heat. Add beef*; season with salt and pepper. Cook, breaking up meat into pieces, until cooked through, 4-6 minutes. Turn off heat; transfer to a plate. Carefully discard any excess grease from pan if necessary. Wipe out pan.

Heat a drizzle of oil in pan used for panko over medium-high heat. Add onion and beans. Season with salt and pepper. Cook, stirring occasionally, until onion is softened, 3-5 minutes.

Add garlic and cook, stirring, until fragrant, 30-60 seconds.

Stir in enchilada sauce, cooked couscous, and half the cilantro. Cook, stirring occasionally, until filling has slightly thickened, 2-3 minutes. Remove from heat.

While filling cooks, in a second small bowl, combine mayonnaise and juice from one lemon wedge (two wedges for 4 servings).

Stir in water 1 tsp at a time until mixture reaches a drizzling consistency. Taste and season with salt and pepper if desired.

Use pan used for beef here. Once filling has thickened, stir in beef.

Once bell peppers are done roasting, remove sheet from oven. Carefully stuff halves with half the filling.

Divide remaining filling between plates. Top with stuffed peppers and spoon lemon drizzle over top; sprinkle with toasted panko and remaining cilantro. Serve with remaining lemon wedges on the side.