Wash the tomatoes and cut them into wedges, removing the seeds if desired.

Set the tomato wedges aside.

In a skillet, melt the butter over medium-low heat.

Sauté the chopped onion in the melted butter until transparent, approximately 10 minutes.

Add the curry powder to the sautéed onions.

Stir to combine the curry powder with the onions.

Continue to sauté the mixture for 4 minutes.

Add the cooked long-grain rice and cooked peas to the skillet.

Season with salt and freshly ground black pepper to taste.

Stir well to thoroughly blend all the flavors.

Transfer the mixture to a container.

Chill the salad in the refrigerator for at least one hour.

Remove the chilled salad from the refrigerator and place it in a serving dish.

Garnish with the reserved tomato wedges and watercress.

Serve chilled.