1Mix buckwheat groats and egg. Cook buckwheat mixture in 10-inch skillet over medium-high heat, stirring constantly, until groats separate and dry.
2Stir in water, butter, vinegar, salt, cumin, onions and garlic. Heat to boiling, stirring constantly; reduce heat.
3Cover and simmer about 5 minutes or until groats are tender and liquid is absorbed. Stir in avocado and tomato.