Special equipment: a tortilla press
Preheat the oven to 400 degrees F. Toast the cumin and coriander seeds in a small skillet over medium heat, tossing occasionally, until fragrant, about 2 minutes. Cool the seeds, and then grind them finely in a spice grinder.
Remove the paper husks from the tomatillos and rinse in cool water to remove any sticky residue; pat dry. Put the tomatillos, poblano, jalapeno, onion and garlic in a mixing bowl. Add half the ground cumin and coriander mixture, the agave or honey and olive oil and mix until the vegetables are coated. Season with some salt and pepper. Put the vegetables in a roasting pan.
Coat the chicken, including the cavity, with grapeseed or canola oil and season with the remaining spice mixture and some salt and pepper. Put the chicken on top of the tomatillo mixture and roast until a meat thermometer inserted in the thickest part of the breast reads 165 degrees F., about 1 hour.
Meanwhile, using your hands, shape the masa into 8 even balls. Cut some wax paper into a few squares slightly larger than the tortilla press. Spray 2 pieces with some nonstick spray. Sandwich a ball of masa between the pieces of wax paper, sprayed sides against the dough, and press in the tortilla press to flatten. Remove the tortilla and set aside. Repeat with the remaining dough, using new pieces of wax paper if necessary.
Heat a cast-iron griddle or pan over medium-high heat and cook the tortillas until golden brown, about 30 seconds per side. Keep warm while you finish the chicken.
Transfer the chicken to a cutting board or platter to rest while you make the salsa verde: Put the vegetable mixture from the roasting pan in a blender along with the half the cilantro and the lime juice and blend until smooth; transfer the salsa to a mixing bowl and season with salt and pepper.
When the chicken is cool enough to handle, remove and discard the skin. Using your hands, shred the meat, put it in a mixing bowl and stir in enough of the salsa verde to moisten. Taste and adjust seasoning or add salsa verde as needed. Put any extra salsa verde in a bowl to serve with the tacos.
Fill the tortillas with the chicken mixture. Serve hot with the sliced radishes, cotija, the remaining cilantro, lime wedges, remaining cilantro, and additional salsa verde in bowls.