1. Preheat oven to 375 degrees. Cook bacon in a large skillet over medium heat until crisp, about 7 minutes. Transfer to a paper-towel-lined plate to drain. Set aside 1/4 cup rendered bacon fat, and leave the rest in the skillet.

2. Make croutons: Toss bread cubes in bacon fat remaining in skillet, coating evenly; season with salt and pepper. Arrange cubes in a single layer on a rimmed baking sheet. Bake until crisp, about 10 minutes. Set aside.

3. Make vinaigrette: In a small bowl, whisk together vinegar and lemon juice; season with salt and pepper. Whisk in reserved bacon fat until emulsified.

4. In a large bowl, combine spinach, peas, feta, croutons, and chives. Pour vinaigrette over spinach mixture, and toss to coat. Divide among serving plates.

5. Fill a deep skillet or wide saucepan with 3 inches of water. Bring to a boil over high heat; reduce to a full simmer. Break 1 egg into a small bowl. Lower the bowl over the simmering water, and quickly slide egg into it. Use a large spoon to keep egg white together, if needed. Simmer until yolk is just set, about 2 1/2 minutes. Using a slotted spoon, transfer egg to a paper-towel-lined plate to drain. Repeat with remaining eggs.

6. To serve, arrange a poached egg and one of the reserved bacon slices on top of each salad. Season with salt and pepper. Serve immediately.