Boil the eggs: Place the eggs in a medium saucepan and cover them with cold water by about 2.5 cm (1 inch). Bring the water to a rolling boil over high heat — you'll see large, vigorous bubbles breaking the surface. Once boiling, cover the pan with a lid, remove it from the heat, and let it sit for exactly 8 minutes. This gives you a firm white and a creamy, fully cooked yolk.

Cool the eggs quickly: While the eggs are resting, fill a large bowl with ice and cold water. After 8 minutes, use a slotted spoon to transfer the eggs directly into the ice bath. Leave them for at least 5 minutes. You'll feel the shells become cool to the touch, which stops the cooking process immediately and makes peeling much easier.

Peel and chop the eggs: Gently tap each egg on the countertop to crack the shell all over, then roll it between your palms to loosen the shell. Peel under a thin stream of running cold water — the water helps slide the shell off cleanly. Once peeled, chop the eggs into small, even pieces about 1 cm (½ inch) wide. You should see a uniform mix of white and yellow.

Mix the dressing: In a large mixing bowl, combine the mayonnaise, Dijon mustard, lemon juice, salt, and pepper. Whisk together until the mixture is pale yellow, smooth, and completely uniform. The mustard and lemon will smell bright and tangy.

Combine everything: Add the chopped eggs, fresh dill, and sliced spring onions to the bowl with the dressing. Use a rubber spatula to fold everything together gently. You want every piece of egg to be coated, but you don't want to mash the eggs into a paste. The final texture should look chunky and creamy, with visible flecks of green dill and spring onion.

Taste and adjust: Take a small spoonful and taste it. The flavour should be rich from the mayonnaise, tangy from the mustard and lemon, and herbaceous from the dill. Add a pinch more salt or a squeeze more lemon if it needs brightening. If you like a little heat, sprinkle in the paprika and stir once more.

Chill (optional but recommended): For the best flavour, cover the bowl and refrigerate for at least 15 minutes. This allows the dill and lemon to meld with the eggs. The salad will look slightly firmer when cold.

Assemble and serve: Toast your bread if desired, lay a few lettuce leaves on one slice, pile a generous scoop of egg salad on top, add a slice of tomato, and close with the other slice of bread. The creamy salad will feel cool against the warm toast.