Preheat oven to 350 degrees. Divide coffee beans, spices, sel gris and oil between two oven-proof casserole dishes. In one dish, toss carrots to coat and cover. Toss beets in the second; cover and roast both dishes until vegetables are easily pierced (45 minutes-1 hour). Remove from oven and peel beets when they are cool enough to handle. Carrots may be peeled, if desired. Set aside.
To make the vinaigrette, place a heavy-bottomed skillet over medium heat and film with one tablespoon of olive oil. Season the fennel with salt, pepper and fennel pollen. Sauté until softened and caramelized. Deglaze the pan with Pernod and remove from heat. To the pan, add tarragon, vinegar, honey, apple juice, salt and Dijon mustard. Stir to combine, transfer to a blender and then purée. Strain vinegar base into a non-reactive bowl and then slowly whisk in remaining olive oil and grape seed oil to emulsify. Season and reserve. Vinaigrette may be refrigerated and used for up to one week.
To make pickled mustard seeds, bring mustard seeds to a boil in a small pot of water, drain and repeat once. Add mustard seeds and remaining ingredients to a pressure cooker and place uncovered over low heat until salt has dissolved and saffron has begun to color the water. Seal pressure cooker and cook for 15 minutes at pressure. Cool and reserve in liquid. Pickled mustard seeds may be stored in the refrigerator for up to one month.
To plate, cut the roasted vegetables into interesting shapes, combine with peas and lightly dress with vinaigrette. Gently toss with fleur de sel and tarragon sprigs. Divide between six plates and finish with pickled mustard seeds, blossoms and caviar.