In the bowl of a Stand Mixer, combine the 0.75 taza leche entera calentada a 110°F warmed to 110°F and ¼ oz levadura seca activa un paquete estándar. Sprinkle 1 teaspoon of the 3 cucharada azúcar granulada over the top and stir gently. Let sit for 5–10 minutes until foamy and fragrant — this confirms your ¼ oz levadura seca activa un paquete estándar is active.

Add the 3.5 taza harina para todo uso más para espolvorear, remaining 3 cucharada azúcar granulada, 0.5 cucharadita sal fina, 3 huevos temperatura ambiente, 1 cucharadita extracto de vainilla pura, and 1 cucharadita ralladura de limón finamente rallada (if using) to the ¼ oz levadura seca activa un paquete estándar mixture. Attach the dough hook and mix on low speed for 2 minutes until a shaggy dough forms. Increase to medium speed and knead for 5 minutes.

With the mixer running on medium-low, add the softened 4 cucharada mantequilla sin sal ablandada, cortada en trozos one piece at a time, waiting about 30 seconds between each addition. Once all the 4 cucharada mantequilla sin sal ablandada, cortada en trozos is incorporated, increase speed to medium-high and knead for 5–7 more minutes until the dough is smooth, elastic, and slightly tacky but not sticky. It will pull cleanly away from the sides of the Mixing Bowl.

Shape the dough into a ball and place it in a lightly greased large Mixing Bowl. Cover tightly with Plastic Wrap and let rise in a warm, draft-free spot for 1.5 to 2 hours, until doubled in size.

Punch down the risen dough and turn it out onto a lightly floured surface. Roll it out to about 1/2-inch thickness. Using a 2.5-inch round cutter (or the rim of a glass), cut out rounds as close together as possible. Re-roll scraps once and cut more rounds — you should get about 16 total.

Place the cut rounds on two Parchment Paper-lined Baking Sheets, spacing them at least 1 inch apart. Cover loosely with Plastic Wrap and let rise again for 30–45 minutes, until puffy and noticeably risen.

Pour the 4 taza aceite vegetal, para freír profundamente into a deep, heavy-bottomed Pot to a depth of at least 3 inches. Heat over medium heat until the 4 taza aceite vegetal, para freír profundamente reaches 350°F. Use a Meat Thermometer — temperature control is the key to perfectly cooked sufganiyot. Too hot and they'll brown before cooking through; too cool and they'll be greasy.

Working in batches of 3–4 (don't crowd the Pot), gently lower the dough rounds into the hot 4 taza aceite vegetal, para freír profundamente using a Slotted Spoon. Fry for 2–2.5 minutes per side, until deep golden brown. Maintain the 4 taza aceite vegetal, para freír profundamente temperature between 340–360°F throughout. Transfer to a Wire Rack lined with paper towels to drain.

Let the donuts cool for at least 10 minutes before filling — they should be warm but not hot. Stir the 1 taza mermelada de fresa suave, sin semillas preferida; until smooth. If it's very thick, warm it briefly in the Microwave and stir. Transfer to a Piping Bag fitted with a long, narrow tip (a Bismarck tip is ideal).

Using a skewer or the tip of a small Knife, poke a hole into the side of each donut, pushing in about 3/4 of the way through the center. Insert the Piping Bag tip into the hole and squeeze in about 1–1.5 tablespoons of 1 taza mermelada de fresa suave, sin semillas preferida; per donut. You'll feel gentle resistance when it's full — don't overfill or the donut will burst.

Generously dust the filled sufganiyot with 3 cucharada azúcar granulada using a fine-mesh Sieve. Serve warm or at room temperature on the day they're made — they're at their absolute best within a few hours of frying.