Pull snow peas from the fridge and let them come to room temperature while prepping the rest of the recipe.
Slice the radishes and onion very thinly. (If you’re using a larger variety, such as watermelon radishes, halve or quarter the slices.) Place in a large bowl. Thinly slice the cabbage, and add it to the bowl. Add juice of ½ lemon and a generous pinch of salt. Use your hands to toss, rubbing the salt and juice into the vegetables. Set aside.
Combine stock, quinoa, salt and pepper in a medium saucepan. Bring to a boil. Cover, reduce heat, and simmer 15 minutes. Remove from heat, and let stand 10 minutes, covered. Fluff with a fork.
While the quinoa cooks, whisk juice of 1 lemon, tahini, oil, water, garlic, salt and pepper in a small bowl.
When the quinoa is ready, add it to the bowl, along with the snap peas, tossing to combine. Transfer to a serving bowl or platter, or divide among 4 plates or shallow bowls. Drizzle with dressing. Sprinkle with almonds, feta and mint. Serve with remaining ½ lemon cut into wedges.