Preheat the oven to 350ºF (180ºC, or gas mark 4), and line a baking sheet with parchment paper.In a small pot, bring the buckwheat groats and water to a simmer over medium-low heat. Cook the grains for 5 to 7 minutes, uncovered, until tender. Strain off any excess liquid, allow it to cool for 10 minutes, then place the buckwheat in a food processor with the oats, dates, agave nectar, vanilla, and salt. Pulse until the mixture is combined, and the oats and dates are slightly broken down.