1. Preheat a gas grill to medium (about 400°F) on one side, or push hot coals to one side of a charcoal grill.
2. Combine first 3 ingredients in a small bowl. Starting at the neck cavity, loosen and lift chicken skin from breasts and legs with fingers.
3. Rub oil mixture under loosened skin.
4. Open beer can; pour out 3/4 cup beer , reserving for another use. (or drink it ♥)
5. Place chicken upright onto can, fitting can into cavity. Pull legs forward to form a tripod, so chicken stands upright.
6. Place chicken upright on grill grate over unheated side.
7. Cover and grill 1 hour and 30 minutes or until a thermometer inserted in thigh registers 165°F, rotating chicken once.
8. Combine mustard, honey, vinegar, and tomato paste in a small bowl.
9. Place chicken and can on a cutting board; let stand 15 minutes. Remove and discard skin and can. Cut chicken into pieces; place on a platter. Drizzle with sauce, and sprinkle with parsley.

Directions for the Oven:

1. Preheat your oven to 375. You may have to remove the second rack in your oven and move the other rack lower, so that the chicken will fit in while standing upright.
2. Combine first 3 ingredients in a small bowl. Starting at the neck cavity, loosen and lift chicken skin from breasts and legs with fingers.
3. Rub oil mixture under loosened skin.
4. Place the can on a baking sheet or oven-safe griddle. Place the chicken over the can. Open the rear cavity of the chicken and carefully place it over the can, so only about an inch of the can is showing.
5. Place the chicken in the oven and roast to an internal temperature of 165 or 73.9°C Depending on the size of your chicken, this can take about 75-90 minutes or so.
6. Combine mustard, honey, vinegar, and tomato paste in a small bowl and drizzle over the chicken.
7. Once the chicken has reached the appropriate internal temperature, let it rest for about 10-15 minutes drizzling with additional mustard sauce before serving.