Cook rice in a sauce pan with 1 ½ c water and a pinch of salt over med-low heat until all the water is absorbed (about 40 minutes).
Slice the tip off the garlic bulb so that most of the cloves are slightly exposed. Wrap in foil packet. Roast at 400F for 30-40 minutes until cloves are lightly golden and very soft.
Slice cherry tomatoes in half. Diced cucumber into ½” – ¾” chunks.
Use knife or fingers to extract the roasted garlic from the bulb. You should have about 2 tbs of mashed paste. Whisk vigorously with olive oil, lemon juice, and salt (to taste, start with 1/8th tsp).
Toss all prepared ingredients in the dressing. Serve cold or at room temperature. Keeps well for up to 1 day.