WASHINGTON — When chef Paul Kennedy first went to work for the Mango Tree chain, about five years ago, the company immediately sent him on a 10-week research trip to Thailand. Hired on a Wednesday, flying to Bangkok on Sunday. He went straight from the airport to a restaurant kitchen, where the first dish he made was som tum, the green papaya salad that is a staple of Thai cooking.

Why that one first? “They wanted me to understand what Thai food is about and how Thai people eat,” he said at the multinational company’s CityCenterDC outpost one day this spring. “It’s all about balance.”

Indeed, the dish is a textbook study in the Thai principles of sour-sweet-salty-spicy, and Kennedy took it all in. At Mango Tree, he used a wooden mortar and pestle he brought from Thailand to lightly bruise the key ingredients, tossing the strips of green papaya with a vibrant dressing just before serving.

In May, Kennedy left Mango Tree. But in true classic style, the som tum is staying right where it is.

GREEN PAPAYA SALAD (SOM TUM THAI)

Serves 4

1 tablespoon tamarind paste

1/4 cup fresh lime juice

3 tablespoons fish sauce

2 tablespoons palm (or light brown) sugar

1 medium green (unripe) papaya (about 1 1/2 pounds)

1 small Thai bird’s-eye chili pepper

1 clove garlic

2 tablespoons toasted, unsalted peanuts

1 tablespoon dried shrimp

4 Chinese long beans

4 halved cherry tomatoes

1. Whisk together the tamarind paste with 2 tablespoons water in a small saucepan over medium heat, until smooth. Stir in lime juice, fish sauce and sugar. Heat, stirring occasionally, until the sugar dissolves, then remove the dressing from the heat to cool.

2. Use a vegetable peeler to peel the papaya, then continue peeling strips of flesh all over the papaya until you get to the seeds. Discard the peel and seeds; cut the strips lengthwise into 1/4-inch pieces. You’ll use 3 cups of the papaya for the salad; reserve the rest for another use.

3. Use a large mortar and pestle (or a deep bowl and a wooden spoon) to lightly mash together the chili pepper and garlic. Add the peanuts and dried shrimp and mash lightly. Cut the long beans into 1-inch pieces, and add them to the mixture. Barely bruise them. Add the cherry tomatoes, and very lightly mash them.

4. Add the green papaya and toss to incorporate. Add the dressing and continue tossing for 2 minutes, until the ingredients are very well coated and the papaya slightly wilts. Divide among bowls, garnish with sprouts of your choice, if desired, and serve.