In a medium or large bowl, mix together the spices and salt. Add the olive oil and tomato paste and stir into a thick paste. Add the chicken and use your hands to massage the marinade thoroughly into each thigh. Marinate chicken overnight or for at least 1 hour (it would also be just fine grilled right away, but marinating is always nice!).
Fire up your grill on high for at least 15 minutes to heat up.
Add chicken and corn to the grill. Grill chicken for 3-5 minutes, or until charred, then flip, reduce the heat to medium and cook for another 2-3 minutes, or until cooked through. Grill the corn for about 10 minutes, turning occasionally.
Cut kernels off the cob and add to a medium bowl along with ¼ cup scallions, lime, jalapeno (if using), garlic (if using), and salt. Toss to combine.
Chop up the chicken into bite-sized pieces.
Make the sauce by adding all ingredients to a blender and blend until smooth.
Warm your tortillas (on an open flame is best!). Add chicken and corn and top with the sauce, pickled onions, remaining scallions and sunflower seeds.