Harissa fish goujons in lettuce cups

Name: Harissa fish goujons in lettuce cups
Ingredients: 700g carrots, halved and cut into long batons; 2 tsp cumin seeds; 1 ½ tbsp olive oil, plus extra for greasing; 1 heaped tbsp harissa; 2 medium eggs, beaten; 4 skinned lemon sole fillets (about 500g/ 1lb 2oz in total), cut into thick strips (about 4 strips per fillet), or other sustainable white fish; 85g fresh breadcrumbs, well seasoned; 1 heaped tbsp tahini; juice 1 lemon; 3-4 Baby Gem lettuces, leaves separated (you'll need about 16 leaves - large ones work best); 4 spring onions, thinly sliced