In the bowl of a stand mixer, stir together 1 cup (240 grams) warm water, 1 tablespoon (12 grams) sugar, and yeast. Let stand until foamy, 5 to 10 minutes.: You will notice a creamy, frothy layer forming on the surface, accompanied by a sweet, bready aroma that signals the yeast is active. This foam is crucial because it confirms fermentation has started, which means your Sufganiyot will rise properly. If nothing appears after 10 minutes, your yeast may be inactive, which will yield a dense dough. Avoid using water warmer than the specified range, as it can kill the yeast and stop fermentation.
Add 2 cups (250 grams) flour, eggs, canola oil, salt, lemon zest, and remaining 5 tablespoons (60 grams) sugar to yeast mixture; using the paddle attachment, beat at low speed just until combined. Add 2 1/4 cups (281 grams) flour; beat just until combined.: At this stage the mixture will be shaggy and slightly sticky, with bits of flour still visible, and you should smell the citrus from the lemon zest . Beating briefly avoids overworking gluten early on, which helps keep the final crumb tender. A common mistake is overmixing now, which tightens the dough and produces chewy sufganiyot later.
Switch to the dough hook attachment. Beat at low speed until a smooth, soft, slightly sticky dough forms, about 14 minutes; add up to remaining 1/4 cup (31 grams) flour, 1 tablespoon (8 grams) at a time, if needed. (Be careful not to add too much flour. It is important for the dough to be soft and slightly sticky so it will have the soft interior we want after frying).: The dough will transform into a cohesive, glossy mass that pulls away from the bowl slightly but still clings when you touch it. It should feel elastic and springy, and you may hear a faint stretching sound as gluten develops. Adding small increments of flour helps you avoid a dry, heavy dough, which would make the interior dense rather than fluffy. If the dough becomes too stiff, your Sufganiyot will be tight and less tender.
Spray a large bowl with cooking spray. Place dough in bowl, turning to grease top. Cover and let rise in a warm, draft-free place (75°F/24°C) until doubled in size, 45 minutes to 1 hour. (Alternatively, cover and refrigerate overnight. When ready to use, proceed as directed.): When the dough has doubled, it will look puffy and hold a gentle indentation when poked with a finger. This rise builds flavor and lightness, and you should detect a faint fermented aroma. Rushing this step is tempting but detrimental, as underproofed dough will not be airy. If your kitchen is cool, the dough will take longer and you may want to find a warmer spot to rise.
Cut out 10 (6-inch) squares of parchment paper, and place 2 to 2 1/2 inches apart on 2 baking sheets. Spray parchment squares with cooking spray.: Preparing the parchment prevents the cut rounds from sticking and makes transferring into hot oil safer, as you can drop the paper and dough into the fryer then remove the paper once the dough has floated. The spacing lets the rounds puff without touching, ensuring even shapes. Crowding the rounds will lead to misshapen sufganiyot as they expand.
Punch down dough; turn out onto a heavily floured surface, and roll to 1/2-inch thickness. Using a 3 1/4-inch round cutter dipped in flour, cut dough. Gently transfer cut dough to prepared parchment squares. Reroll scraps, and let stand for 5 to 10 minutes; cut scraps. Discard remaining dough. Cover and let rise in a warm, draft-free place (75°F/24°C) until puffed, about 30 minutes.: As you roll, the dough should feel soft with a slightly tacky surface dusted with flour. The rounds should hold their shape and show a light, airy texture at the edges. Handle them gently to preserve the gas pockets that create a tender interior. Overworking at this stage deflates the dough and results in dense sufganiyot.
In a large heavy-bottomed saucepan, pour vegetable oil to a depth of 2 inches, and heat over medium heat until a deep-fry thermometer registers 365°F (185°C).: After the second rise the rounds will look noticeably puffed and soft, like little pillows ready to fry. The additional rest relaxes the gluten, producing more tender pastries. If the rounds remain flat, the oil will soak in rather than creating a crisp shell, so ensure they have visibly puffed before frying.
Line a large rimmed baking sheet with paper towels.: The oil should shimmer slightly and give off only a faint scent of warmth, not smoke. Frying at the correct temperature creates a quick golden crust that seals moisture inside. If the oil is too cool the sufganiyot will absorb excess oil and become greasy; too hot and they will brown too fast, leaving raw interior. Maintain consistent temperature between batches for even results.
Working in batches, using parchment squares, gently pick up sufganiyot and add to oil. (Do not place parchment paper in oil.) Fry until golden brown, about 2 1/2 minutes, turning halfway through frying. Using a spider strainer, remove sufganiyot from oil, and place on prepared pan. Let cool completely.: The paper towels will absorb excess oil, and you should see faint oil sheen on them after draining, indicating correct frying. A clean, organized draining area helps you manage hot pastries safely. Skipping this step leaves the finished sufganiyot overly oily and less pleasant to eat.
Using a small paring knife, make a hole in side of each cooled sufganiyah; using a small wooden skewer, hollow inside of each sufganiyah.: As they fry you will hear a gentle bubbling and see the surface transform to a uniform golden color. Turning halfway ensures even browning and a symmetrical crust. Remove with a spider strainer when done and transfer to the prepared pan. Frying too long will darken them and risk drying the interior, while under frying leaves them pale and doughy.
In a medium bowl, whisk together jelly, vanilla bean paste, cinnamon, and allspice. Place in a squeeze bottle. Pipe jelly mixture into sufganiyot, being careful not to overfill. (Each sufganiyah will hold about 50 grams. If it is overfilled, it will just leak back out, which can be wiped off but gets sticky). Dip tops in Vanilla Glaze, letting excess drip off. Let stand until glaze is set. Best served same day.: Cooling allows the interior to set so you can hollow and fill without collapsing. You will notice the aroma shift from sizzling oil to sweet dough and jam. Rushing to fill when still very hot can melt the filling and glaze, creating a mess.
Using a small paring knife, make a hole in side of each cooled sufganiyah; using a small wooden skewer, hollow inside of each sufganiyah: When you hollow them out you should see a soft, airy interior with small uniform air pockets, which is the sign of proper fermentation. Work gently to avoid tearing the exterior shell. A common error is cutting too large a hole which can cause fillings to leak out.
In a medium bowl, whisk together jelly, vanilla bean paste, cinnamon, and allspice. Place in a squeeze bottle: The mixture will be glossy and fragrant, with a warm spice aroma. Using a squeeze bottle gives you control while piping, preventing overfilling. If the jelly is too stiff, warm it slightly to make piping easier, but avoid overheating which thins it too much and increases leaking.
Pipe jelly mixture into sufganiyot, being careful not to overfill. Dip tops in Vanilla Glaze, letting excess drip off. Let stand until glaze is set: As you pipe, you will feel gentle resistance when the cavity is full and may see the dough expand slightly as the filling settles. The glaze should form a satiny coating that firms to the touch in a few minutes, adding visual shine and sweetness. Overfilling leads to leakage and stickiness, which can be messy for serving.