1. Preheat oven to 400 degrees. In a medium sized bowl, combine potato pieces with a glug or two of olive oil, a good sprinkling of sea salt, and a few grinds of black pepper, tossing evenly to coat. Roast potatoes in a single layer on a foil lined baking sheet for 10 minutes. 2. Meanwhile, halve and slice any large radishes into wedges, leaving smaller ones whole. Using the same bowl that you tossed the potatoes in, combine radishes with olive oil, sea salt and black pepper; mix well to evenly coat. 3. Once the potatoes have roasted for 10 minutes, using a wooden spatula or spoon, gently push potatoes around, being careful to keep skin intact (as best as possible). Push potatoes to one side of pan, adding radishes in a single layer to the other side. Continue to roast for another 10-12 minutes or until potatoes and radishes are tender, shaking pan midway through (at 10 minutes start checking to make sure radishes do not overcook). 4. Meanwhile, in a small skillet, heat 1 teaspoon of extra virgin olive oil over medium heat. When hot, add black mustard seeds and whole cumin seeds and gently mix. Cook for about a minute, until fragrant, being mindful that black mustard seeds will start to pop. I used my wooden spoon to shield the seeds from popping all over the place. Remove pan from heat and set aside. 5. Remove pan from oven and allow vegetables to completely cool (making it easy to remove from pan without sticking ? especially the potatoes). Halve small radishes. Transfer roasted radishes and potatoes to a bowl. Add yogurt, black mustard/cumin seed mixture and green onions, folding with a spatula to combine. Add lemon juice mixture by the teaspoonful until you reach desired taste. I added one and a half teaspoons of lemon juice-salt-sugar mixture. Fold to combine. Cover mixture with plastic wrap and refrigerate for at least an hour to allow flavors to develop. Bring salad to room temperature before enjoying.