Step 1 Preheat oven to 180°C. Mix garlic, 1 teaspoon of the mustard, honey and 1 tablespoon of the lemon juice in a small bowl. Place each chicken fillet on a 20cm x 30cm piece of foil. Spoon lemon mixture over chicken; season with cracked black pepper. Fold foil edges to enclose chicken fillets in 2 parcels. Place parcels on a baking tray; cook for 15 minutes, or until chicken is cooked through. Remove parcels from oven; leave to cool. Shred chicken; set aside.
Step 2 Line a separate baking tray with baking paper. Place sourdough and prosciutto on tray, and spray sourdough lightly with olive oil. Bake, turning sourdough once, for 8–10 minutes, or until both sourdough and prosciutto are crisp and golden. Set aside to cool. Snap prosciutto into shards.
Step 3 Bring a medium saucepan of water to the boil; immerse green beans to blanch until just tender. Refresh beans under cold running water, then drain well.
Step 4 Put shredded chicken, toasted sourdough, prosciutto, green beans, lettuce and cucumber in a large bowl. Whisk yoghurt and remaining mustard with lemon juice and anchovy in a medium bowl to make dressing.
Step 6 Divide salad among 4 plates, drizzle with dressing and top each with half a soft-boiled egg.