Special equipment: Thick gardening gloves or rubber dish gloves
For the oil: Using your palm or the back of a chef knife, gently crush the garlic until it is slightly split, but still intact. Place the garlic into an airtight container and cover with olive oil. Seal the container with a lid and let it steep overnight prior to using.
For the frittata: In a large bowl, add the half-and-half, eggs, thyme and garlic. Stir together, cover with plastic and refrigerate overnight.
Preheat the oven to 350 degrees F. Before making the frittata, bring the egg mixture to room temperature.
In a 6-quart pot of salted boiling water, drop in the stinging nettles using thick gardening gloves to handle. Blanch for 30 seconds and remove using tongs. Drain in a colander. Squeeze as much water out as possible. On a baking tray, spread the blanched nettles to cool. Roughly chop the cooled nettles and set aside.
Heat a 10-inch saucepan over medium-high heat, and add 1 tablespoon of the olive oil. Once the oil is shimmering, cook the nettles and spring onions until most of the moisture has evaporated, about 3 minutes. Season with salt and set aside.
Brush a 9-by-13-inch baking dish with the garlic oil. Line the bottom and sides of the baking dish with the potato slices. Sprinkle bottom with 1 cup of the Cheddar. Bake in until the cheese melts, about 5 minutes. This will help create a crust.
Remove from the oven and spread the nettle and spring onion mixture over the potato crust, followed by the spinach, and the remaining cup of Cheddar. Pour the egg mixture evenly over the cheese, making sure the egg gets into every corner of the baking dish. Lay the asparagus and tomatoes over the top of egg mixture and sprinkle with the Parmesan. Bake until the top is slightly golden brown, 40 minutes.
Rest the frittata for 10 minutes before slicing.
For the salad: In a large bowl, whisk together the shallots, tarragon, thyme, salt, lemon juice, lime juice and orange juice. Slowly whisk in the oil until emulsified. In another large bowl, add the miner's lettuce, sorrel, watercress and salad greens, and toss with the dressing until well incorporated.
Slice the frittata and serve with the dressed salad.
Stinging nettles can be found at your local farmer's market. The garlic oil will keep for at least 1 month at room temperature.
A viewer or guest of the show, who may not be a professional cook, provided this recipe. It has not been tested for home use.