Heat the oil in a medium omelet or frying-pan. Add the onion and garlic and fry until they are soft. Stir in the tomatoes and pimientos and fry for a further 3 minutes. Remove the pan from the heat and keep hot. Combine the eggs, seasoning and milk until they are well blended. Stir in the peas.

Preheat the grill (broiler) to high.

Return the pan to the heat and pour the egg mixture into the pan, tilting it so that the bottom is evenly covered. Reduce the heat to low. Using a palette knife or spatula, lift the edges of the omelet and, at the same time, tilt the pan away from you so that the liquid egg escapes from the top and runs on to the pan. Put the pan down flat over the heat until the omelet sets.

Remove the pan from the heat and place it under the grill (broiler). Grill (broil) for 2 minutes, or until the top of the omelet has set. Remove from the heat.

Carefully slide the omelet on to a serving dish and cut into wedges. Serve at once.